Function distinct_on

lib/sqlalchemy/dialects/postgresql/ext.py:542–555

apply a DISTINCT_ON to a SELECT statement e.g.:: stmt = select(tbl).ext(distinct_on(t.c.some_col)) this supersedes the previous approach of using ``select(tbl).distinct(t.c.some_col))`` to apply a similar construct. .. versionadded:: 2.1

(*expr: _ColumnExpressionArgument[Any])

def distinct_on(*expr: _ColumnExpressionArgument[Any]) -> DistinctOnClause:
    """apply a DISTINCT_ON to a SELECT statement

    e.g.::

        stmt = select(tbl).ext(distinct_on(t.c.some_col))

    this supersedes the previous approach of using
    ``select(tbl).distinct(t.c.some_col))`` to apply a similar construct.

    .. versionadded:: 2.1

    """
    return DistinctOnClause(expr)


class DistinctOnClause(SyntaxExtension, expression.ClauseElement):