IN 子查询

随同 IN 子查询，可返回多个满足 IN 或 NOT IN 条件的行，但仅可返回一列。

此示例展示在 SELECT 语句中 NOT IN 子查询的使用：

SELECT DISTINCT customer_num FROM orders
   WHERE order_num NOT IN
      (SELECT order_num FROM items
         WHERE stock_num = 1);

要获取附加的信息，请参阅 IN 条件。