using 等價于 join 操作中的 on雌桑,如:
SELECT id FROM table1 AS a
JOIN table2 AS b
ON a.id=b.id
等價于:
SELECT id FROM table1 AS a
JOIN table2 AS b
using(id)
using 等價于 join 操作中的 on雌桑,如:
SELECT id FROM table1 AS a
JOIN table2 AS b
ON a.id=b.id
等價于:
SELECT id FROM table1 AS a
JOIN table2 AS b
using(id)