Thread: Bug report for plpgsql

PostgreSQL 17.0 (Debian 17.0-1.pgdg120+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 12.2.0-14) 12.2.0, 64-bit

ERROR: column reference "column_name" is ambiguous
DETAIL: It could refer to either a PL/pgSQL variable or a table column.
CONTEXT: PL/pgSQL function some_function() line X at SQL statement

1. Create a table with a unique constraint:

CREATE TABLE example_table (    id uuid PRIMARY KEY DEFAULT gen_random_uuid(),    column_name text NOT NULL,    value numeric NOT NULL,    UNIQUE (column_name)
);

1. Create a function that returns a table with a column name matching one in the table:

CREATE OR REPLACE FUNCTION example_function(p_column_name text, p_value numeric)    RETURNS TABLE(column_name text, value numeric)    LANGUAGE plpgsql
AS
$$
BEGININSERT INTO example_table (column_name, value)    VALUES (p_column_name, p_value)    ON CONFLICT (column_name)    DO UPDATE SET value = example_table.value + EXCLUDED.value    RETURNING column_name, value INTO column_name, value;
    RETURN NEXT;
END;
$$;

1. Call the function:

SELECT * FROM example_function('test', 42);

ERROR: column reference "column_name" is ambiguous
DETAIL: It could refer to either a PL/pgSQL variable or a table column.