ClickHouse/tests/queries/0_stateless/00681_duplicate_columns_inside_union_all_stas_sviridov.sql

DROP TABLE IF EXISTS test_00681;

CREATE TABLE test_00681(x Int32) ENGINE = Log;
INSERT INTO test_00681 VALUES (123);

SELECT a1 
FROM
(
    SELECT x AS a1, x AS a2 FROM test_00681
    UNION ALL
    SELECT x, x FROM test_00681
);

DROP TABLE test_00681;