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Handle derived tables with set operations

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This commit adds support for derived tables (i.e., subqueries) that
incorporate set operations, like:

    SELECT * FROM (((SELECT 1) UNION (SELECT 2)) t1 AS NATURAL JOIN t2)

This introduces a bit of complexity around determining whether a left
paren starts a subquery, starts a nested join, or belongs to an
already-started subquery. The details are explained in a comment within
the patch.
This commit is contained in:
Nikhil Benesch 2019-06-09 15:01:59 -04:00
parent 1998910bfa
commit 8bee74277a
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2 changed files with 100 additions and 24 deletions
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30
tests/sqlparser_common.rs
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@ -1848,6 +1848,32 @@ fn parse_derived_tables() {
let sql = "SELECT * FROM t NATURAL JOIN (((SELECT 1)))";
let _ = verified_only_select(sql);
// TODO: add assertions
let sql = "SELECT * FROM (((SELECT 1) UNION (SELECT 2)) AS t1 NATURAL JOIN t2)";
let select = verified_only_select(sql);
let from = only(select.from);
assert_eq!(
from.relation,
TableFactor::NestedJoin(Box::new(TableWithJoins {
relation: TableFactor::Derived {
lateral: false,
subquery: Box::new(verified_query("(SELECT 1) UNION (SELECT 2)")),
alias: Some(TableAlias {
name: "t1".into(),
columns: vec![],
})
},
joins: vec![Join {
relation: TableFactor::Table {
name: SQLObjectName(vec!["t2".into()]),
alias: None,
args: vec![],
with_hints: vec![],
},
join_operator: JoinOperator::Inner(JoinConstraint::Natural),
}],
}))
)
}
#[test]
@ -2360,7 +2386,9 @@ fn lateral_derived() {
let sql = "SELECT * FROM a LEFT JOIN LATERAL (b CROSS JOIN c)";
let res = parse_sql_statements(sql);
assert_eq!(
ParserError::ParserError("Expected subquery after LATERAL, found nested join".to_string()),
ParserError::ParserError(
"Expected SELECT or a subquery in the query body, found: b".to_string()
),
res.unwrap_err()
);
}