博主依然不想打字,又向你仍来了一堆代码。。。 13(续)在SELECT中用COUNT()以及联合mysql> SELECT customers.cust_id,COUNT(orders.order_num) AS num_ord -> FROM customer ...
博主依然不想打字,又向你仍来了一堆代码。。。
13(续)
在SELECT中用COUNT()以及联合
mysql> SELECT customers.cust_id,COUNT(orders.order_num) AS num_ord -> FROM customers INNER JOIN orders -> ON customers.cust_id=orders.cust_id -> GROUP BY cust_id;+------------+---------+| cust_id | num_ord |+------------+---------+| 1000000001 | 2 || 1000000003 | 1 || 1000000004 | 1 || 1000000005 | 1 |+------------+---------+4 rows in set (0.00 sec)
原标题:SQL必知必会 14
关键词:sql
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