如何返回在 MySQL 中具有相同列值的行？
为此使用GROUPBY子句。让我们首先创建一个表-
mysql> create table DemoTable -> ( -> StudentId int, -> StudentMarks int -> );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable values(23,58); mysql> insert into DemoTable values(25,89); mysql> insert into DemoTable values(26,58); mysql> insert into DemoTable values(28,98);
使用select语句显示表中的所有记录-
mysql> select *from DemoTable;输出结果
+-----------+--------------+ | StudentId | StudentMarks | +-----------+--------------+ | 23 | 58 | | 25 | 89 | | 26 | 58 | | 28 | 98 | +-----------+--------------+ 4 rows in set (0.00 sec)
这是返回在MySQL中具有相同列值的行的查询-
mysql> select StudentMarks from DemoTable -> group by StudentMarks -> having sum(StudentId=23) > 0 and -> sum(StudentId=26) > 0;输出结果
+--------------+ | StudentMarks | +--------------+ | 58 | +--------------+ 1 row in set (0.00 sec)