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FEAT: Support 5.1 - Handled empty order-by clause by defaulting it to SELECT NULL #457

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Merged
merged 2 commits into from
Jun 16, 2025
Merged

FEAT: Support 5.1 - Handled empty order-by clause by defaulting it to SELECT NULL #457

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c2c3da9
Handled empty order-by clause by defaulting it to SELECT NULL
NandanaRaol Jun 5, 2025
6e82813
removed sql
NandanaRaol Jun 5, 2025
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20 changes: 17 additions & 3 deletions mssql/compiler.py
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Original file line number Diff line number Diff line change
Expand Up @@ -133,13 +133,18 @@ def _as_sql_variance(self, compiler, connection):
return self.as_sql(compiler, connection, function=function)

def _as_sql_window(self, compiler, connection, template=None):
# Get the expressions supported by the backend
connection.ops.check_expression_support(self)
# Raise an error if window expressions are not supported.
if not connection.features.supports_over_clause:
raise NotSupportedError("This backend does not support window expressions.")
# Compile the source expression for the window function.
expr_sql, params = compiler.compile(self.source_expression)
# Initialize window SQL parts and parameters.
window_sql, window_params = [], ()

# Handle PARTITION BY clause if present.
if self.partition_by is not None:
# Compile the PARTITION BY clause.
sql_expr, sql_params = self.partition_by.as_sql(
compiler=compiler,
connection=connection,
Expand All @@ -148,21 +153,30 @@ def _as_sql_window(self, compiler, connection, template=None):
window_sql.append(sql_expr)
window_params += tuple(sql_params)

# Handle ORDER BY clause if present.
if self.order_by is not None:
# Compile the ORDER BY clause.
order_sql, order_params = compiler.compile(self.order_by)
# Handles cases where order_by compiles to empty
if not order_sql.strip():
order_sql = "ORDER BY (SELECT NULL)"
order_params = ()
window_sql.append(order_sql)
window_params += tuple(order_params)
else:
# MSSQL window functions require an OVER clause with ORDER BY
# Default to ORDER BY (SELECT NULL) if no order_by is specified.
window_sql.append('ORDER BY (SELECT NULL)')

# Handle frame specification if present.
if self.frame:
# Compile the frame clause.
frame_sql, frame_params = compiler.compile(self.frame)
window_sql.append(frame_sql)
window_params += tuple(frame_params)

# Use provided template or default to self.template.
template = template or self.template

# Return the formatted SQL and combined parameters.
return (
template % {"expression": expr_sql, "window": " ".join(window_sql).strip()},
(*params, *window_params),
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