mirrors/django
1
0
Fork 0
mirror of https://github.com/django/django.git synced 2025-09-01 00:08:13 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 2

Refs #25367 -- Moved Oracle Exists() handling to contextual methods.

Browse source 
Oracle requires the EXISTS expression to be wrapped in a CASE WHEN in
the following cases.

1. When part of a SELECT clause.
2. When part of a ORDER BY clause.
3. When compared against another expression in the WHERE clause.

This commit moves the systematic CASE WHEN wrapping of Exists.as_oracle
to contextual .select_format, Lookup.as_oracle, and OrderBy.as_oracle
methods in order to avoid unnecessary wrapping.
This commit is contained in:
Simon Charette 2019-08-11 02:12:11 -04:00 • committed by Mariusz Felisiak
parent fff5186d32
commit efa1908f66
4 changed files with 40 additions and 7 deletions
Download patch file Download diff file Expand all files Collapse all files

24
django/db/models/expressions.py
View file

@ -1075,12 +1075,11 @@ class Exists(Subquery):
sql = 'NOT {}'.format(sql)
return sql, params
def as_oracle(self, compiler, connection, template=None, **extra_context):
# Oracle doesn't allow EXISTS() in the SELECT list, so wrap it with a
# CASE WHEN expression. Change the template since the When expression
# requires a left hand side (column) to compare against.
sql, params = self.as_sql(compiler, connection, template, **extra_context)
sql = 'CASE WHEN {} THEN 1 ELSE 0 END'.format(sql)
def select_format(self, compiler, sql, params):
# Wrap EXISTS() with a CASE WHEN expression if a database backend
# (e.g. Oracle) doesn't support boolean expression in the SELECT list.
if not compiler.connection.features.supports_boolean_expr_in_select_clause:
sql = 'CASE WHEN {} THEN 1 ELSE 0 END'.format(sql)
return sql, params
@ -1140,6 +1139,19 @@ class OrderBy(BaseExpression):
template = 'IF(ISNULL(%(expression)s),0,1), %(expression)s %(ordering)s '
return self.as_sql(compiler, connection, template=template)
def as_oracle(self, compiler, connection):
# Oracle doesn't allow ORDER BY EXISTS() unless it's wrapped in
# a CASE WHEN.
if isinstance(self.expression, Exists):
copy = self.copy()
# XXX: Use Case(When(self.lhs)) once support for boolean
# expressions is added to When.
exists_sql, params = compiler.compile(self.expression)
case_sql = 'CASE WHEN %s THEN 1 ELSE 0 END' % exists_sql
copy.expression = RawSQL(case_sql, params)
return copy.as_sql(compiler, connection)
return self.as_sql(compiler, connection)
def get_group_by_cols(self, alias=None):
cols = []
for source in self.get_source_expressions():