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fix(render): preserve NOT in negated NULL predicates #16

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fix(render): preserve NOT in negated NULL predicates #16

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05a1192
fix(render): preserve NOT when rendering negated IS [NOT] NULL predic…
Sivadheeraj5356 Oct 28, 2026
1fbf35e
test: cover NOT with IS [NOT] NULL predicate rendering
Sivadheeraj5356 Oct 28, 2026
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9 changes: 9 additions & 0 deletions mindsdb/utilities/render/sqlalchemy_render.py
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Original file line number Diff line number Diff line change
Expand Up @@ -284,6 +284,15 @@ def to_expression(self, t):
arg1 = self.to_expression(t.args[1])

op = t.op.lower()
if (
op in ("is", "is not")
and isinstance(t.args[1], ast.Constant)
and t.args[1].value is None
):
# to_expression wraps constants in a label; with a labeled NULL
# operand SQLAlchemy cannot negate the predicate, so NOT (x IS NULL)
# lost its NOT. A bare sa.null() keeps is_/is_not invertible.
arg1 = sa.null()
if op in ("in", "not in"):
if t.args[1].parentheses:
arg1 = [arg1]
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15 changes: 15 additions & 0 deletions tests/unit/render/test_sqlalchemyrender.py
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,21 @@


class TestMysqlRender:
def test_not_is_null(self):
# NOT must survive rendering of negated IS [NOT] NULL predicates
# (regression: a labeled NULL operand made the inversion a no-op)
cases = {
"SELECT * FROM tb1 WHERE NOT (x IS NULL)": "SELECT * FROM tb1 WHERE x IS NOT NULL",
"SELECT * FROM tb1 WHERE NOT x IS NULL": "SELECT * FROM tb1 WHERE x IS NOT NULL",
"SELECT * FROM tb1 WHERE NOT (x IS NOT NULL)": "SELECT * FROM tb1 WHERE x IS NULL",
"SELECT * FROM tb1 WHERE x IS NULL": "SELECT * FROM tb1 WHERE x IS NULL",
"SELECT * FROM tb1 WHERE x IS NOT NULL": "SELECT * FROM tb1 WHERE x IS NOT NULL",
}
for sql_in, expected in cases.items():
query = parse_sql(sql_in)
sql = SqlalchemyRender("mysql").get_string(query, with_failback=False)
assert sql.replace("\n", "").replace("\t", "") == expected, sql_in

def test_create_table(self):
query = CreateTable(
name="tbl1",
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