cpython/Doc/library/sqlite3.rst
Christian Heimes 81ee3efede Merged revisions 62425-62429,62434-62436,62441,62444,62446-62448,62450-62455,62463,62465-62466,62469,62474,62476-62478,62480,62485,62492,62497-62498,62500,62507,62513-62514,62516,62521,62531,62535,62545-62546,62548-62551,62553-62559,62569,62574,62577,62593,62595,62604-62606,62608,62616,62626-62627,62636,62638,62644-62645,62647-62648,62651-62653,62656,62661,62663,62680,62686-62687,62696,62699-62703,62711 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk

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  r62425 | andrew.kuchling | 2008-04-21 03:45:57 +0200 (Mon, 21 Apr 2008) | 1 line

  Comment typo
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  r62426 | mark.dickinson | 2008-04-21 03:55:50 +0200 (Mon, 21 Apr 2008) | 2 lines

  Silence 'r may be used uninitialized' compiler warning.
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  r62427 | andrew.kuchling | 2008-04-21 04:08:00 +0200 (Mon, 21 Apr 2008) | 1 line

  Markup fix
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  r62428 | andrew.kuchling | 2008-04-21 04:08:13 +0200 (Mon, 21 Apr 2008) | 1 line

  Wording changes
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  r62429 | andrew.kuchling | 2008-04-21 04:14:24 +0200 (Mon, 21 Apr 2008) | 1 line

  Add various items
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  r62434 | thomas.heller | 2008-04-21 15:46:55 +0200 (Mon, 21 Apr 2008) | 1 line

  Fix typo.
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  r62435 | david.goodger | 2008-04-21 16:40:22 +0200 (Mon, 21 Apr 2008) | 1 line

  corrections ("reStructuredText" is one word)
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  r62436 | david.goodger | 2008-04-21 16:43:33 +0200 (Mon, 21 Apr 2008) | 1 line

  capitalization
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  r62441 | gregory.p.smith | 2008-04-21 19:46:40 +0200 (Mon, 21 Apr 2008) | 2 lines

  explicitly flush after the ... since there wasn't a newline
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  r62444 | jeroen.ruigrok | 2008-04-21 22:15:39 +0200 (Mon, 21 Apr 2008) | 2 lines

  Windows x64 also falls under VER_PLATFORM_WIN32_NT.
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  r62446 | gregory.p.smith | 2008-04-21 23:31:08 +0200 (Mon, 21 Apr 2008) | 3 lines

  If sys.stdin is not a tty, fall back to default_getpass after printing
  a warning instead of failing with a termios.error.
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  r62447 | mark.dickinson | 2008-04-22 00:32:24 +0200 (Tue, 22 Apr 2008) | 8 lines

  test_math and test_cmath are failing on the FreeBSD 6.2 trunk buildbot,
  apparently because tanh(-0.) loses the sign of zero on that platform.
  If true, this is a bug in FreeBSD.

  Added a configure test to verify this.  I still need to figure out
  how best to deal with this failure.
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  r62448 | amaury.forgeotdarc | 2008-04-22 00:35:30 +0200 (Tue, 22 Apr 2008) | 7 lines

  Issue 2665: On Windows, sys.stderr does not contain a valid file when running without a console.
  It seems to work, but will fail at the first flush.

  This causes IDLE to crash when too many warnings are printed.

  Will backport.
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  r62450 | benjamin.peterson | 2008-04-22 00:57:00 +0200 (Tue, 22 Apr 2008) | 2 lines

  Fix Sphinx warnings
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  r62451 | mark.dickinson | 2008-04-22 02:54:27 +0200 (Tue, 22 Apr 2008) | 3 lines

  Make configure test for tanh(-0.) == -0. committed in r62447 actually
  work.  (The test wasn't properly linked with libm.  Sigh.)
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  r62452 | benjamin.peterson | 2008-04-22 04:16:03 +0200 (Tue, 22 Apr 2008) | 2 lines

  Various io doc updates
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  r62453 | neal.norwitz | 2008-04-22 07:07:47 +0200 (Tue, 22 Apr 2008) | 1 line

  Add Thomas Lee
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  r62454 | gregory.p.smith | 2008-04-22 10:08:41 +0200 (Tue, 22 Apr 2008) | 8 lines

  Major improvements:
  * Default to using /dev/tty for the password prompt and input before
    falling back to sys.stdin and sys.stderr.
  * Use sys.stderr instead of sys.stdout.
  * print the 'password may be echoed' warning to stream used to display
    the prompt rather than always sys.stderr.
  * warn() with GetPassWarning when input may be echoed.
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  r62455 | gregory.p.smith | 2008-04-22 10:11:33 +0200 (Tue, 22 Apr 2008) | 2 lines

  update the getpass entry
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  r62463 | amaury.forgeotdarc | 2008-04-22 23:14:41 +0200 (Tue, 22 Apr 2008) | 5 lines

  Issue #2670: urllib2.build_opener() failed when two handlers
  derive the same default base class.

  Will backport.
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  r62465 | skip.montanaro | 2008-04-23 00:45:09 +0200 (Wed, 23 Apr 2008) | 3 lines

  Factor in documentation changes from issue 1753732.
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  r62466 | gregory.p.smith | 2008-04-23 03:06:42 +0200 (Wed, 23 Apr 2008) | 2 lines

  syntax fixup
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  r62469 | benjamin.peterson | 2008-04-23 22:38:06 +0200 (Wed, 23 Apr 2008) | 2 lines

  #2673 Fix example typo in optparse docs
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  r62474 | martin.v.loewis | 2008-04-24 11:50:50 +0200 (Thu, 24 Apr 2008) | 2 lines

  Add Guilherme Polo.
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  r62476 | martin.v.loewis | 2008-04-24 15:16:36 +0200 (Thu, 24 Apr 2008) | 3 lines

  Remove Py_Refcnt, Py_Type, Py_Size, as they were added only
  for backwards compatibility, yet 2.5 did not have them at all.
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  r62477 | martin.v.loewis | 2008-04-24 15:17:24 +0200 (Thu, 24 Apr 2008) | 2 lines

  Fix typo.
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  r62478 | martin.v.loewis | 2008-04-24 15:18:03 +0200 (Thu, 24 Apr 2008) | 2 lines

  Add Jesus Cea.
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  r62480 | amaury.forgeotdarc | 2008-04-24 20:07:05 +0200 (Thu, 24 Apr 2008) | 4 lines

  Issue2681: the literal 0o8 was wrongly accepted, and evaluated as float(0.0).
  This happened only when 8 is the first digit.
  Credits go to Lukas Meuser.
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  r62485 | amaury.forgeotdarc | 2008-04-24 22:10:26 +0200 (Thu, 24 Apr 2008) | 5 lines

  Disable gc when running test_trace, or we may record the __del__ of collected objects.

  See http://mail.python.org/pipermail/python-checkins/2008-April/068633.html
  the extra events perfectly match several calls to socket._fileobject.__del__()
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  r62492 | neal.norwitz | 2008-04-25 05:40:17 +0200 (Fri, 25 Apr 2008) | 1 line

  Fix typo (now -> no)
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  r62497 | armin.rigo | 2008-04-25 11:35:18 +0200 (Fri, 25 Apr 2008) | 2 lines

  A new crasher.
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  r62498 | thomas.heller | 2008-04-25 17:44:16 +0200 (Fri, 25 Apr 2008) | 1 line

  Add from_buffer and from_buffer_copy class methods to ctypes types.
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  r62500 | mark.dickinson | 2008-04-25 18:59:09 +0200 (Fri, 25 Apr 2008) | 3 lines

  Issue 2635: fix bug in the fix_sentence_endings option to textwrap.fill.
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  r62507 | benjamin.peterson | 2008-04-25 23:43:56 +0200 (Fri, 25 Apr 2008) | 2 lines

  Allow test_import to work when it is invoked directly
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  r62513 | georg.brandl | 2008-04-26 20:31:07 +0200 (Sat, 26 Apr 2008) | 2 lines

  #2691: document PyLong (s)size_t APIs, patch by Alexander Belopolsky.
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  r62514 | georg.brandl | 2008-04-26 20:32:17 +0200 (Sat, 26 Apr 2008) | 2 lines

  Add missing return type to dealloc.
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  r62516 | alexandre.vassalotti | 2008-04-27 02:52:24 +0200 (Sun, 27 Apr 2008) | 2 lines

  Fixed URL of PEP 205 in weakref's module docstring.
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  r62521 | georg.brandl | 2008-04-27 11:39:59 +0200 (Sun, 27 Apr 2008) | 2 lines

  #2677: add note that not all functions may accept keyword args.
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  r62531 | georg.brandl | 2008-04-27 19:38:55 +0200 (Sun, 27 Apr 2008) | 2 lines

  Use correct XHTML tags.
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  r62535 | benjamin.peterson | 2008-04-27 20:14:39 +0200 (Sun, 27 Apr 2008) | 2 lines

  #2700 Document PyNumber_ToBase
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  r62545 | skip.montanaro | 2008-04-27 22:53:57 +0200 (Sun, 27 Apr 2008) | 1 line

  minor wording changes, rewrap a few lines
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  r62546 | kurt.kaiser | 2008-04-27 23:07:41 +0200 (Sun, 27 Apr 2008) | 7 lines

  Home / Control-A toggles between left margin and end of leading white
  space.  Patch 1196903 Jeff Shute.

  M    idlelib/PyShell.py
  M    idlelib/EditorWindow.py
  M    idlelib/NEWS.txt
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  r62548 | kurt.kaiser | 2008-04-27 23:38:05 +0200 (Sun, 27 Apr 2008) | 2 lines

  Improved AutoCompleteWindow logic.  Patch 2062 Tal Einat.
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  r62549 | kurt.kaiser | 2008-04-27 23:52:19 +0200 (Sun, 27 Apr 2008) | 4 lines

  Autocompletion of filenames now support alternate separators, e.g. the
  '/' char on Windows.  Patch 2061 Tal Einat.
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  r62550 | skip.montanaro | 2008-04-28 00:49:56 +0200 (Mon, 28 Apr 2008) | 6 lines

  A few small changes:
  * The only exception we should catch when trying to import cStringIO is an
    ImportError.
  * Delete the function signatures embedded in the mk*temp docstrings.
  * The tempdir global variable was initialized twice.
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  r62551 | skip.montanaro | 2008-04-28 00:52:02 +0200 (Mon, 28 Apr 2008) | 4 lines

  Wrap some long paragraphs and include the default values for optional
  function parameters.
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  r62553 | skip.montanaro | 2008-04-28 04:57:23 +0200 (Mon, 28 Apr 2008) | 7 lines

  Minor cleanups:
  * Avoid creating unused local variables where we can.  Where we can't prefix
    the unused variables with '_'.
  * Avoid shadowing builtins where it won't change the external interface of a
    function.
  * Use None as default path arg to readmodule and readmodule_ex.
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  r62554 | skip.montanaro | 2008-04-28 04:59:45 +0200 (Mon, 28 Apr 2008) | 6 lines

  Correct documentation to match implementation: "Class" instead of
  "class_descriptor", "Function" instead of "function_descriptor".  Note
  default path value for readmodule*.  Wrap some long paragraphs.  Don't
  mention 'inpackage' which isn't part of the public API.
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  r62555 | brett.cannon | 2008-04-28 05:23:50 +0200 (Mon, 28 Apr 2008) | 5 lines

  Fix a bug introduced by the warnings rewrite where tracebacks were being
  improperly indented.

  Closes issue #2699.
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  r62556 | skip.montanaro | 2008-04-28 05:25:37 +0200 (Mon, 28 Apr 2008) | 2 lines

  Wrap some long lines.
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  r62557 | skip.montanaro | 2008-04-28 05:27:53 +0200 (Mon, 28 Apr 2008) | 6 lines

  Get rid of _test(), _main(), _debug() and _check().  Tests are no longer
  needed (better set available in Lib/test/test_robotparser.py).  Clean up a
  few PEP 8 nits (compound statements on a single line, whitespace around
  operators).
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  r62558 | brett.cannon | 2008-04-28 06:50:06 +0200 (Mon, 28 Apr 2008) | 3 lines

  Rename the test_traceback_print() function to traceback_print() to prevent
  test_capi from automatically calling the function.
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  r62559 | georg.brandl | 2008-04-28 07:16:30 +0200 (Mon, 28 Apr 2008) | 2 lines

  Fix markup.
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  r62569 | amaury.forgeotdarc | 2008-04-28 23:07:06 +0200 (Mon, 28 Apr 2008) | 5 lines

  test_sundry performs minimal tests (a simple import...) on modules that are not tested otherwise.

  Some of them now have tests and can be removed.
  Only 70 to go...
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  r62574 | andrew.kuchling | 2008-04-29 04:03:54 +0200 (Tue, 29 Apr 2008) | 1 line

  Strip down SSL docs; I'm not managing to get test programs working, so I'll just give a minimal description
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  r62577 | martin.v.loewis | 2008-04-29 08:10:53 +0200 (Tue, 29 Apr 2008) | 2 lines

  Add Rodrigo and Heiko.
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  r62593 | nick.coghlan | 2008-04-30 16:23:36 +0200 (Wed, 30 Apr 2008) | 1 line

  Update command line usage documentation to reflect 2.6 changes (also includes some minor cleanups). Addresses TODO list issue 2258
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  r62595 | andrew.kuchling | 2008-04-30 18:19:55 +0200 (Wed, 30 Apr 2008) | 1 line

  Typo fix
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  r62604 | benjamin.peterson | 2008-04-30 23:03:58 +0200 (Wed, 30 Apr 2008) | 2 lines

  make test_support's captured_output a bit more robust when exceptions happen
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  r62605 | georg.brandl | 2008-04-30 23:08:42 +0200 (Wed, 30 Apr 2008) | 2 lines

  #1748: use functools.wraps instead of rolling own metadata update.
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  r62606 | benjamin.peterson | 2008-04-30 23:25:55 +0200 (Wed, 30 Apr 2008) | 2 lines

  Remove some from __future__ import with_statements
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  r62608 | benjamin.peterson | 2008-05-01 00:03:36 +0200 (Thu, 01 May 2008) | 2 lines

  Fix typo in whatsnew
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  r62616 | georg.brandl | 2008-05-01 20:24:32 +0200 (Thu, 01 May 2008) | 2 lines

  Fix synopsis.
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  r62626 | brett.cannon | 2008-05-02 04:25:09 +0200 (Fri, 02 May 2008) | 6 lines

  Fix a backwards-compatibility mistake where a new optional argument for
  warnings.showwarning() was being used. This broke pre-existing replacements for
  the function since they didn't support the extra argument.

  Closes issue 2705.
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  r62627 | gregory.p.smith | 2008-05-02 09:26:52 +0200 (Fri, 02 May 2008) | 20 lines

  This should fix issue2632.  A long description of the two competing
  problems is in the bug report (one old, one recently introduced trying
  to fix the old one).  In short:

  buffer data during socket._fileobject.read() and readlines() within a
  cStringIO object instead of a [] of str()s returned from the recv()
  call.

  This prevents excessive memory use due to the size parameter being
  passed to recv() being grossly larger than the actual size of the data
  returned *and* prevents excessive cpu usage due to looping in python
  calling recv() with a very tiny size value if min() is used as the
  previous memory-use bug "fix" did.

  It also documents what the socket._fileobject._rbufsize member is
  actually used for.

  This is a candidate for back porting to 2.5.
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  r62636 | mark.hammond | 2008-05-02 14:48:15 +0200 (Fri, 02 May 2008) | 2 lines

  #2581: Vista UAC/elevation support for bdist_wininst
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  r62638 | facundo.batista | 2008-05-02 19:39:00 +0200 (Fri, 02 May 2008) | 3 lines


  Fixed some test structures. Thanks Mark Dickinson.
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  r62644 | ronald.oussoren | 2008-05-02 21:45:11 +0200 (Fri, 02 May 2008) | 7 lines

  Fix for issue #2573: Can't change the framework name on OS X builds

  This introduces a new configure option: --with-framework-name=NAME
  (defaulting to 'Python'). This allows you to install several copies
  of the Python framework with different names (such as a normal build
  and a debug build).
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  r62645 | ronald.oussoren | 2008-05-02 21:58:56 +0200 (Fri, 02 May 2008) | 2 lines

  Finish fix for issue2573, previous patch was incomplete.
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  r62647 | martin.v.loewis | 2008-05-02 23:30:20 +0200 (Fri, 02 May 2008) | 13 lines

  Merged revisions 62263-62646 via svnmerge from
  svn+ssh://pythondev@svn.python.org/sandbox/trunk/2to3/lib2to3

  ........
    r62470 | david.wolever | 2008-04-24 02:11:07 +0200 (Do, 24 Apr 2008) | 3 lines

    Fixed up and applied the patch for #2431 -- speeding up 2to3 with a lookup table.
  ........
    r62646 | martin.v.loewis | 2008-05-02 23:29:27 +0200 (Fr, 02 Mai 2008) | 2 lines

    Fix whitespace.
  ........
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  r62648 | ronald.oussoren | 2008-05-02 23:42:35 +0200 (Fri, 02 May 2008) | 4 lines

  Fix for #1905: PythonLauncher not working correctly on OSX 10.5/Leopard

  This fixes both Python Launchar and the terminalcommand module.
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  r62651 | ronald.oussoren | 2008-05-02 23:54:56 +0200 (Fri, 02 May 2008) | 2 lines

  Fix for issue #2520 (cannot import macerrors)
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  r62652 | benjamin.peterson | 2008-05-03 00:12:58 +0200 (Sat, 03 May 2008) | 2 lines

  capitalization nit for reStructuredText
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  r62653 | brett.cannon | 2008-05-03 03:02:41 +0200 (Sat, 03 May 2008) | 2 lines

  Fix some indentation errors.
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  r62656 | brett.cannon | 2008-05-03 05:19:39 +0200 (Sat, 03 May 2008) | 6 lines

  Fix the C implementation of 'warnings' to infer the filename of the module that
  raised an exception properly when __file__ is not set, __name__ == '__main__',
  and sys.argv[0] is a false value.

  Closes issue2743.
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  r62661 | amaury.forgeotdarc | 2008-05-03 14:21:13 +0200 (Sat, 03 May 2008) | 8 lines

  In test_io, StatefulIncrementalDecoderTest was not part of the test suite.
  And of course, the test failed:
  a bytearray was used without reason in io.TextIOWrapper.tell().

  The difference is that iterating over bytes (i.e. str in python2.6) returns 1-char bytes,
  whereas bytearrays yield integers.
  This code should still work with python3.0
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  r62663 | benjamin.peterson | 2008-05-03 17:56:42 +0200 (Sat, 03 May 2008) | 2 lines

  The compiling struct is now passed around to all AST helpers (see issue 2720)
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  r62680 | benjamin.peterson | 2008-05-03 23:35:18 +0200 (Sat, 03 May 2008) | 2 lines

  Moved testing of builtin types out of test_builtin and into type specific modules
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  r62686 | mark.dickinson | 2008-05-04 04:25:46 +0200 (Sun, 04 May 2008) | 4 lines

  Make sure that Context traps and flags dictionaries have values 0 and 1
  (as documented) rather than True and False.
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  r62687 | benjamin.peterson | 2008-05-04 05:05:49 +0200 (Sun, 04 May 2008) | 2 lines

  Fix typo in whatsnew
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  r62696 | georg.brandl | 2008-05-04 11:15:04 +0200 (Sun, 04 May 2008) | 2 lines

  #2752: wrong meaning of '' for socket host.
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  r62699 | christian.heimes | 2008-05-04 13:50:53 +0200 (Sun, 04 May 2008) | 1 line

  Added note that Python requires at least Win2k SP4
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  r62700 | gerhard.haering | 2008-05-04 14:59:57 +0200 (Sun, 04 May 2008) | 3 lines

  SQLite requires 64-bit integers in order to build. So the whole HAVE_LONG_LONG
  #ifdefing was useless.
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  r62701 | gerhard.haering | 2008-05-04 15:15:12 +0200 (Sun, 04 May 2008) | 3 lines

  Applied sqliterow-richcmp.diff patch from Thomas Heller in Issue2152. The
  sqlite3.Row type is now correctly hashable.
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  r62702 | gerhard.haering | 2008-05-04 15:42:44 +0200 (Sun, 04 May 2008) | 5 lines

  Implemented feature request 2157: Converter names are cut off at '('
  characters. This avoids the common case of something like 'NUMBER(10)' not
  being parsed as 'NUMBER', like expected. Also corrected the docs about
  converter names being case-sensitive. They aren't any longer.
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  r62703 | georg.brandl | 2008-05-04 17:45:05 +0200 (Sun, 04 May 2008) | 2 lines

  #2757: Remove spare newline.
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  r62711 | benjamin.peterson | 2008-05-04 21:10:02 +0200 (Sun, 04 May 2008) | 2 lines

  Fix typo in bugs.rst
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2008-05-04 22:42:01 +00:00

765 lines
29 KiB
ReStructuredText

:mod:`sqlite3` --- DB-API 2.0 interface for SQLite databases
============================================================
.. module:: sqlite3
:synopsis: A DB-API 2.0 implementation using SQLite 3.x.
.. sectionauthor:: Gerhard Häring <gh@ghaering.de>
SQLite is a C library that provides a lightweight disk-based database that
doesn't require a separate server process and allows accessing the database
using a nonstandard variant of the SQL query language. Some applications can use
SQLite for internal data storage. It's also possible to prototype an
application using SQLite and then port the code to a larger database such as
PostgreSQL or Oracle.
pysqlite was written by Gerhard Häring and provides a SQL interface compliant
with the DB-API 2.0 specification described by :pep:`249`.
To use the module, you must first create a :class:`Connection` object that
represents the database. Here the data will be stored in the
:file:`/tmp/example` file::
conn = sqlite3.connect('/tmp/example')
You can also supply the special name ``:memory:`` to create a database in RAM.
Once you have a :class:`Connection`, you can create a :class:`Cursor` object
and call its :meth:`execute` method to perform SQL commands::
c = conn.cursor()
# Create table
c.execute('''create table stocks
(date text, trans text, symbol text,
qty real, price real)''')
# Insert a row of data
c.execute("""insert into stocks
values ('2006-01-05','BUY','RHAT',100,35.14)""")
# Save (commit) the changes
conn.commit()
# We can also close the cursor if we are done with it
c.close()
Usually your SQL operations will need to use values from Python variables. You
shouldn't assemble your query using Python's string operations because doing so
is insecure; it makes your program vulnerable to an SQL injection attack.
Instead, use the DB-API's parameter substitution. Put ``?`` as a placeholder
wherever you want to use a value, and then provide a tuple of values as the
second argument to the cursor's :meth:`execute` method. (Other database modules
may use a different placeholder, such as ``%s`` or ``:1``.) For example::
# Never do this -- insecure!
symbol = 'IBM'
c.execute("... where symbol = '%s'" % symbol)
# Do this instead
t = (symbol,)
c.execute('select * from stocks where symbol=?', t)
# Larger example
for t in (('2006-03-28', 'BUY', 'IBM', 1000, 45.00),
('2006-04-05', 'BUY', 'MSOFT', 1000, 72.00),
('2006-04-06', 'SELL', 'IBM', 500, 53.00),
):
c.execute('insert into stocks values (?,?,?,?,?)', t)
To retrieve data after executing a SELECT statement, you can either treat the
cursor as an :term:`iterator`, call the cursor's :meth:`fetchone` method to
retrieve a single matching row, or call :meth:`fetchall` to get a list of the
matching rows.
This example uses the iterator form::
>>> c = conn.cursor()
>>> c.execute('select * from stocks order by price')
>>> for row in c:
... print(row)
...
(u'2006-01-05', u'BUY', u'RHAT', 100, 35.140000000000001)
(u'2006-03-28', u'BUY', u'IBM', 1000, 45.0)
(u'2006-04-06', u'SELL', u'IBM', 500, 53.0)
(u'2006-04-05', u'BUY', u'MSOFT', 1000, 72.0)
>>>
.. seealso::
http://www.pysqlite.org
The pysqlite web page.
http://www.sqlite.org
The SQLite web page; the documentation describes the syntax and the available
data types for the supported SQL dialect.
:pep:`249` - Database API Specification 2.0
PEP written by Marc-André Lemburg.
.. _sqlite3-module-contents:
Module functions and constants
------------------------------
.. data:: PARSE_DECLTYPES
This constant is meant to be used with the *detect_types* parameter of the
:func:`connect` function.
Setting it makes the :mod:`sqlite3` module parse the declared type for each
column it returns. It will parse out the first word of the declared type,
i. e. for "integer primary key", it will parse out "integer", or for
"number(10)" it will parse out "number". Then for that column, it will look
into the converters dictionary and use the converter function registered for
that type there.
.. data:: PARSE_COLNAMES
This constant is meant to be used with the *detect_types* parameter of the
:func:`connect` function.
Setting this makes the SQLite interface parse the column name for each column it
returns. It will look for a string formed [mytype] in there, and then decide
that 'mytype' is the type of the column. It will try to find an entry of
'mytype' in the converters dictionary and then use the converter function found
there to return the value. The column name found in :attr:`cursor.description`
is only the first word of the column name, i. e. if you use something like
``'as "x [datetime]"'`` in your SQL, then we will parse out everything until the
first blank for the column name: the column name would simply be "x".
.. function:: connect(database[, timeout, isolation_level, detect_types, factory])
Opens a connection to the SQLite database file *database*. You can use
``":memory:"`` to open a database connection to a database that resides in RAM
instead of on disk.
When a database is accessed by multiple connections, and one of the processes
modifies the database, the SQLite database is locked until that transaction is
committed. The *timeout* parameter specifies how long the connection should wait
for the lock to go away until raising an exception. The default for the timeout
parameter is 5.0 (five seconds).
For the *isolation_level* parameter, please see the
:attr:`Connection.isolation_level` property of :class:`Connection` objects.
SQLite natively supports only the types TEXT, INTEGER, FLOAT, BLOB and NULL. If
you want to use other types you must add support for them yourself. The
*detect_types* parameter and the using custom **converters** registered with the
module-level :func:`register_converter` function allow you to easily do that.
*detect_types* defaults to 0 (i. e. off, no type detection), you can set it to
any combination of :const:`PARSE_DECLTYPES` and :const:`PARSE_COLNAMES` to turn
type detection on.
By default, the :mod:`sqlite3` module uses its :class:`Connection` class for the
connect call. You can, however, subclass the :class:`Connection` class and make
:func:`connect` use your class instead by providing your class for the *factory*
parameter.
Consult the section :ref:`sqlite3-types` of this manual for details.
The :mod:`sqlite3` module internally uses a statement cache to avoid SQL parsing
overhead. If you want to explicitly set the number of statements that are cached
for the connection, you can set the *cached_statements* parameter. The currently
implemented default is to cache 100 statements.
.. function:: register_converter(typename, callable)
Registers a callable to convert a bytestring from the database into a custom
Python type. The callable will be invoked for all database values that are of
the type *typename*. Confer the parameter *detect_types* of the :func:`connect`
function for how the type detection works. Note that the case of *typename* and
the name of the type in your query must match!
.. function:: register_adapter(type, callable)
Registers a callable to convert the custom Python type *type* into one of
SQLite's supported types. The callable *callable* accepts as single parameter
the Python value, and must return a value of the following types: int,
float, str, bytes (UTF-8 encoded) or buffer.
.. function:: complete_statement(sql)
Returns :const:`True` if the string *sql* contains one or more complete SQL
statements terminated by semicolons. It does not verify that the SQL is
syntactically correct, only that there are no unclosed string literals and the
statement is terminated by a semicolon.
This can be used to build a shell for SQLite, as in the following example:
.. literalinclude:: ../includes/sqlite3/complete_statement.py
.. function:: enable_callback_tracebacks(flag)
By default you will not get any tracebacks in user-defined functions,
aggregates, converters, authorizer callbacks etc. If you want to debug them, you
can call this function with *flag* as True. Afterwards, you will get tracebacks
from callbacks on ``sys.stderr``. Use :const:`False` to disable the feature
again.
.. _sqlite3-connection-objects:
Connection Objects
------------------
A :class:`Connection` instance has the following attributes and methods:
.. attribute:: Connection.isolation_level
Get or set the current isolation level. None for autocommit mode or one of
"DEFERRED", "IMMEDIATE" or "EXLUSIVE". See section
:ref:`sqlite3-controlling-transactions` for a more detailed explanation.
.. method:: Connection.cursor([cursorClass])
The cursor method accepts a single optional parameter *cursorClass*. If
supplied, this must be a custom cursor class that extends
:class:`sqlite3.Cursor`.
.. method:: Connection.commit()
This method commits the current transaction. If you don't call this method,
anything you did since the last call to commit() is not visible from from
other database connections. If you wonder why you don't see the data you've
written to the database, please check you didn't forget to call this method.
.. method:: Connection.rollback()
This method rolls back any changes to the database since the last call to
:meth:`commit`.
.. method:: Connection.close()
This closes the database connection. Note that this does not automatically
call :meth:`commit`. If you just close your database connection without
calling :meth:`commit` first, your changes will be lost!
.. method:: Connection.execute(sql, [parameters])
This is a nonstandard shortcut that creates an intermediate cursor object by
calling the cursor method, then calls the cursor's :meth:`execute` method with
the parameters given.
.. method:: Connection.executemany(sql, [parameters])
This is a nonstandard shortcut that creates an intermediate cursor object by
calling the cursor method, then calls the cursor's :meth:`executemany` method
with the parameters given.
.. method:: Connection.executescript(sql_script)
This is a nonstandard shortcut that creates an intermediate cursor object by
calling the cursor method, then calls the cursor's :meth:`executescript` method
with the parameters given.
.. method:: Connection.create_function(name, num_params, func)
Creates a user-defined function that you can later use from within SQL
statements under the function name *name*. *num_params* is the number of
parameters the function accepts, and *func* is a Python callable that is called
as the SQL function.
The function can return any of the types supported by SQLite: bytes, str, int,
float, buffer and None.
Example:
.. literalinclude:: ../includes/sqlite3/md5func.py
.. method:: Connection.create_aggregate(name, num_params, aggregate_class)
Creates a user-defined aggregate function.
The aggregate class must implement a ``step`` method, which accepts the number
of parameters *num_params*, and a ``finalize`` method which will return the
final result of the aggregate.
The ``finalize`` method can return any of the types supported by SQLite:
bytes, str, int, float, buffer and None.
Example:
.. literalinclude:: ../includes/sqlite3/mysumaggr.py
.. method:: Connection.create_collation(name, callable)
Creates a collation with the specified *name* and *callable*. The callable will
be passed two string arguments. It should return -1 if the first is ordered
lower than the second, 0 if they are ordered equal and 1 if the first is ordered
higher than the second. Note that this controls sorting (ORDER BY in SQL) so
your comparisons don't affect other SQL operations.
Note that the callable will get its parameters as Python bytestrings, which will
normally be encoded in UTF-8.
The following example shows a custom collation that sorts "the wrong way":
.. literalinclude:: ../includes/sqlite3/collation_reverse.py
To remove a collation, call ``create_collation`` with None as callable::
con.create_collation("reverse", None)
.. method:: Connection.interrupt()
You can call this method from a different thread to abort any queries that might
be executing on the connection. The query will then abort and the caller will
get an exception.
.. method:: Connection.set_authorizer(authorizer_callback)
This routine registers a callback. The callback is invoked for each attempt to
access a column of a table in the database. The callback should return
:const:`SQLITE_OK` if access is allowed, :const:`SQLITE_DENY` if the entire SQL
statement should be aborted with an error and :const:`SQLITE_IGNORE` if the
column should be treated as a NULL value. These constants are available in the
:mod:`sqlite3` module.
The first argument to the callback signifies what kind of operation is to be
authorized. The second and third argument will be arguments or :const:`None`
depending on the first argument. The 4th argument is the name of the database
("main", "temp", etc.) if applicable. The 5th argument is the name of the
inner-most trigger or view that is responsible for the access attempt or
:const:`None` if this access attempt is directly from input SQL code.
Please consult the SQLite documentation about the possible values for the first
argument and the meaning of the second and third argument depending on the first
one. All necessary constants are available in the :mod:`sqlite3` module.
.. method:: Connection.set_progress_handler(handler, n)
This routine registers a callback. The callback is invoked for every *n*
instructions of the SQLite virtual machine. This is useful if you want to
get called from SQLite during long-running operations, for example to update
a GUI.
If you want to clear any previously installed progress handler, call the
method with :const:`None` for *handler*.
.. attribute:: Connection.row_factory
You can change this attribute to a callable that accepts the cursor and the
original row as a tuple and will return the real result row. This way, you can
implement more advanced ways of returning results, such as returning an object
that can also access columns by name.
Example:
.. literalinclude:: ../includes/sqlite3/row_factory.py
If returning a tuple doesn't suffice and you want name-based access to
columns, you should consider setting :attr:`row_factory` to the
highly-optimized :class:`sqlite3.Row` type. :class:`Row` provides both
index-based and case-insensitive name-based access to columns with almost no
memory overhead. It will probably be better than your own custom
dictionary-based approach or even a db_row based solution.
.. XXX what's a db_row-based solution?
.. attribute:: Connection.text_factory
Using this attribute you can control what objects are returned for the TEXT data
type. By default, this attribute is set to :class:`str` and the
:mod:`sqlite3` module will return strings for TEXT. If you want to
return bytestrings instead, you can set it to :class:`bytes`.
For efficiency reasons, there's also a way to return :class:`str` objects
only for non-ASCII data, and :class:`bytes` otherwise. To activate it, set
this attribute to :const:`sqlite3.OptimizedUnicode`.
You can also set it to any other callable that accepts a single bytestring
parameter and returns the resulting object.
See the following example code for illustration:
.. literalinclude:: ../includes/sqlite3/text_factory.py
.. attribute:: Connection.total_changes
Returns the total number of database rows that have been modified, inserted, or
deleted since the database connection was opened.
.. attribute:: Connection.iterdump
Returns an iterator to dump the database in an SQL text format. Useful when
saving an in-memory database for later restoration. This function provides
the same capabilities as the :kbd:`.dump` command in the :program:`sqlite3`
shell.
Example::
# Convert file existing_db.db to SQL dump file dump.sql
import sqlite3, os
con = sqlite3.connect('existing_db.db')
full_dump = os.linesep.join([line for line in con.iterdump()])
f = open('dump.sql', 'w')
f.writelines(full_dump)
f.close()
.. _sqlite3-cursor-objects:
Cursor Objects
--------------
A :class:`Cursor` instance has the following attributes and methods:
.. method:: Cursor.execute(sql, [parameters])
Executes an SQL statement. The SQL statement may be parametrized (i. e.
placeholders instead of SQL literals). The :mod:`sqlite3` module supports two
kinds of placeholders: question marks (qmark style) and named placeholders
(named style).
This example shows how to use parameters with qmark style:
.. literalinclude:: ../includes/sqlite3/execute_1.py
This example shows how to use the named style:
.. literalinclude:: ../includes/sqlite3/execute_2.py
:meth:`execute` will only execute a single SQL statement. If you try to execute
more than one statement with it, it will raise a Warning. Use
:meth:`executescript` if you want to execute multiple SQL statements with one
call.
.. method:: Cursor.executemany(sql, seq_of_parameters)
Executes an SQL command against all parameter sequences or mappings found in
the sequence *sql*. The :mod:`sqlite3` module also allows using an
:term:`iterator` yielding parameters instead of a sequence.
.. literalinclude:: ../includes/sqlite3/executemany_1.py
Here's a shorter example using a :term:`generator`:
.. literalinclude:: ../includes/sqlite3/executemany_2.py
.. method:: Cursor.executescript(sql_script)
This is a nonstandard convenience method for executing multiple SQL statements
at once. It issues a COMMIT statement first, then executes the SQL script it
gets as a parameter.
*sql_script* can be an instance of :class:`str` or :class:`bytes`.
Example:
.. literalinclude:: ../includes/sqlite3/executescript.py
.. method:: Cursor.fetchone()
Fetches the next row of a query result set, returning a single sequence,
or ``None`` when no more data is available.
.. method:: Cursor.fetchmany([size=cursor.arraysize])
Fetches the next set of rows of a query result, returning a list. An empty
list is returned when no more rows are available.
The number of rows to fetch per call is specified by the *size* parameter.
If it is not given, the cursor's arraysize determines the number of rows
to be fetched. The method should try to fetch as many rows as indicated by
the size parameter. If this is not possible due to the specified number of
rows not being available, fewer rows may be returned.
Note there are performance considerations involved with the *size* parameter.
For optimal performance, it is usually best to use the arraysize attribute.
If the *size* parameter is used, then it is best for it to retain the same
value from one :meth:`fetchmany` call to the next.
.. method:: Cursor.fetchall()
Fetches all (remaining) rows of a query result, returning a list. Note that
the cursor's arraysize attribute can affect the performance of this operation.
An empty list is returned when no rows are available.
.. attribute:: Cursor.rowcount
Although the :class:`Cursor` class of the :mod:`sqlite3` module implements this
attribute, the database engine's own support for the determination of "rows
affected"/"rows selected" is quirky.
For ``DELETE`` statements, SQLite reports :attr:`rowcount` as 0 if you make a
``DELETE FROM table`` without any condition.
For :meth:`executemany` statements, the number of modifications are summed up
into :attr:`rowcount`.
As required by the Python DB API Spec, the :attr:`rowcount` attribute "is -1 in
case no executeXX() has been performed on the cursor or the rowcount of the last
operation is not determinable by the interface".
This includes ``SELECT`` statements because we cannot determine the number of
rows a query produced until all rows were fetched.
.. attribute:: Cursor.lastrowid
This read-only attribute provides the rowid of the last modified row. It is
only set if you issued a ``INSERT`` statement using the :meth:`execute`
method. For operations other than ``INSERT`` or when :meth:`executemany` is
called, :attr:`lastrowid` is set to :const:`None`.
.. _sqlite3-types:
SQLite and Python types
-----------------------
Introduction
^^^^^^^^^^^^
SQLite natively supports the following types: NULL, INTEGER, REAL, TEXT, BLOB.
The following Python types can thus be sent to SQLite without any problem:
+-------------------------------+-------------+
| Python type | SQLite type |
+===============================+=============+
| ``None`` | NULL |
+-------------------------------+-------------+
| :class:`int` | INTEGER |
+-------------------------------+-------------+
| :class:`float` | REAL |
+-------------------------------+-------------+
| :class:`bytes` (UTF8-encoded) | TEXT |
+-------------------------------+-------------+
| :class:`str` | TEXT |
+-------------------------------+-------------+
| :class:`buffer` | BLOB |
+-------------------------------+-------------+
This is how SQLite types are converted to Python types by default:
+-------------+---------------------------------------------+
| SQLite type | Python type |
+=============+=============================================+
| ``NULL`` | None |
+-------------+---------------------------------------------+
| ``INTEGER`` | int |
+-------------+---------------------------------------------+
| ``REAL`` | float |
+-------------+---------------------------------------------+
| ``TEXT`` | depends on text_factory, str by default |
+-------------+---------------------------------------------+
| ``BLOB`` | buffer |
+-------------+---------------------------------------------+
The type system of the :mod:`sqlite3` module is extensible in two ways: you can
store additional Python types in a SQLite database via object adaptation, and
you can let the :mod:`sqlite3` module convert SQLite types to different Python
types via converters.
Using adapters to store additional Python types in SQLite databases
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
As described before, SQLite supports only a limited set of types natively. To
use other Python types with SQLite, you must **adapt** them to one of the
sqlite3 module's supported types for SQLite: one of NoneType, int, float,
str, bytes, buffer.
The :mod:`sqlite3` module uses Python object adaptation, as described in
:pep:`246` for this. The protocol to use is :class:`PrepareProtocol`.
There are two ways to enable the :mod:`sqlite3` module to adapt a custom Python
type to one of the supported ones.
Letting your object adapt itself
""""""""""""""""""""""""""""""""
This is a good approach if you write the class yourself. Let's suppose you have
a class like this::
class Point(object):
def __init__(self, x, y):
self.x, self.y = x, y
Now you want to store the point in a single SQLite column. First you'll have to
choose one of the supported types first to be used for representing the point.
Let's just use str and separate the coordinates using a semicolon. Then you need
to give your class a method ``__conform__(self, protocol)`` which must return
the converted value. The parameter *protocol* will be :class:`PrepareProtocol`.
.. literalinclude:: ../includes/sqlite3/adapter_point_1.py
Registering an adapter callable
"""""""""""""""""""""""""""""""
The other possibility is to create a function that converts the type to the
string representation and register the function with :meth:`register_adapter`.
.. literalinclude:: ../includes/sqlite3/adapter_point_2.py
The :mod:`sqlite3` module has two default adapters for Python's built-in
:class:`datetime.date` and :class:`datetime.datetime` types. Now let's suppose
we want to store :class:`datetime.datetime` objects not in ISO representation,
but as a Unix timestamp.
.. literalinclude:: ../includes/sqlite3/adapter_datetime.py
Converting SQLite values to custom Python types
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Writing an adapter lets you send custom Python types to SQLite. But to make it
really useful we need to make the Python to SQLite to Python roundtrip work.
Enter converters.
Let's go back to the :class:`Point` class. We stored the x and y coordinates
separated via semicolons as strings in SQLite.
First, we'll define a converter function that accepts the string as a parameter
and constructs a :class:`Point` object from it.
.. note::
Converter functions **always** get called with a string, no matter under which
data type you sent the value to SQLite.
::
def convert_point(s):
x, y = map(float, s.split(";"))
return Point(x, y)
Now you need to make the :mod:`sqlite3` module know that what you select from
the database is actually a point. There are two ways of doing this:
* Implicitly via the declared type
* Explicitly via the column name
Both ways are described in section :ref:`sqlite3-module-contents`, in the entries
for the constants :const:`PARSE_DECLTYPES` and :const:`PARSE_COLNAMES`.
The following example illustrates both approaches.
.. literalinclude:: ../includes/sqlite3/converter_point.py
Default adapters and converters
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
There are default adapters for the date and datetime types in the datetime
module. They will be sent as ISO dates/ISO timestamps to SQLite.
The default converters are registered under the name "date" for
:class:`datetime.date` and under the name "timestamp" for
:class:`datetime.datetime`.
This way, you can use date/timestamps from Python without any additional
fiddling in most cases. The format of the adapters is also compatible with the
experimental SQLite date/time functions.
The following example demonstrates this.
.. literalinclude:: ../includes/sqlite3/pysqlite_datetime.py
.. _sqlite3-controlling-transactions:
Controlling Transactions
------------------------
By default, the :mod:`sqlite3` module opens transactions implicitly before a
Data Modification Language (DML) statement (i.e. INSERT/UPDATE/DELETE/REPLACE),
and commits transactions implicitly before a non-DML, non-query statement (i. e.
anything other than SELECT/INSERT/UPDATE/DELETE/REPLACE).
So if you are within a transaction and issue a command like ``CREATE TABLE
...``, ``VACUUM``, ``PRAGMA``, the :mod:`sqlite3` module will commit implicitly
before executing that command. There are two reasons for doing that. The first
is that some of these commands don't work within transactions. The other reason
is that pysqlite needs to keep track of the transaction state (if a transaction
is active or not).
You can control which kind of "BEGIN" statements pysqlite implicitly executes
(or none at all) via the *isolation_level* parameter to the :func:`connect`
call, or via the :attr:`isolation_level` property of connections.
If you want **autocommit mode**, then set :attr:`isolation_level` to None.
Otherwise leave it at its default, which will result in a plain "BEGIN"
statement, or set it to one of SQLite's supported isolation levels: DEFERRED,
IMMEDIATE or EXCLUSIVE.
Using pysqlite efficiently
--------------------------
Using shortcut methods
^^^^^^^^^^^^^^^^^^^^^^
Using the nonstandard :meth:`execute`, :meth:`executemany` and
:meth:`executescript` methods of the :class:`Connection` object, your code can
be written more concisely because you don't have to create the (often
superfluous) :class:`Cursor` objects explicitly. Instead, the :class:`Cursor`
objects are created implicitly and these shortcut methods return the cursor
objects. This way, you can execute a SELECT statement and iterate over it
directly using only a single call on the :class:`Connection` object.
.. literalinclude:: ../includes/sqlite3/shortcut_methods.py
Accessing columns by name instead of by index
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
One useful feature of the :mod:`sqlite3` module is the builtin
:class:`sqlite3.Row` class designed to be used as a row factory.
Rows wrapped with this class can be accessed both by index (like tuples) and
case-insensitively by name:
.. literalinclude:: ../includes/sqlite3/rowclass.py
Using the connection as a context manager
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Connection objects can be used as context managers
that automatically commit or rollback transactions. In the event of an
exception, the transaction is rolled back; otherwise, the transaction is
committed:
.. literalinclude:: ../includes/sqlite3/ctx_manager.py