使用MySQL在另一列中获取具有两个不同值的所有记录
为此，可以使用GROUPBYHAVING子句。
让我们首先创建一个表-
mysql> create table DemoTable751 ( StudentName varchar(100), SubjectName varchar(100) );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable751 values('John','MySQL');
mysql> insert into DemoTable751 values('John','MongoDB');
mysql> insert into DemoTable751 values('Sam','MySQL');
mysql> insert into DemoTable751 values('Carol','Java');
mysql> insert into DemoTable751 values('David','MySQL');
mysql> insert into DemoTable751 values('Carol','MongoDB');使用select语句显示表中的所有记录-
mysql> select *from DemoTable751;
这将产生以下输出-
+-------------+-------------+ | StudentName | SubjectName | +-------------+-------------+ | John | MySQL | | John | MongoDB | | Sam | MySQL | | Carol | Java | | David | MySQL | | Carol | MongoDB | +-------------+-------------+ 6 rows in set (0.00 sec)
以下是查询以获取MySQL中具有两个不同值的所有记录-
mysql> select StudentName from DemoTable751 group by StudentName having count(SubjectName) > 1;
这将产生以下输出-
+-------------+ | StudentName | +-------------+ | John | | Carol | +-------------+ 2 rows in set (0.00 sec)