Crie um
AUTO_INCREMENT campo na nova tabela e omita-o da lista de valores:CREATE TABLE NEW_TABLE (id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, col1 …, col2 …, …);
INSERT
INTO new_table (col1, col2, …)
SELECT col1, col2
FROM old_table_1
UNION ALL
SELECT col1, col2
FROM old_table_2
UNION ALL
…
