从特定的MySQL行仅获取一个值？
为此，将SELECTINTO变量与where子句一起使用。让我们首先创建一个表-
mysql> create table DemoTable1896 ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentName varchar(20), StudentMarks int );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable1896(StudentName,StudentMarks) values('Chris',56);
mysql> insert into DemoTable1896(StudentName,StudentMarks) values('David',98);
mysql> insert into DemoTable1896(StudentName,StudentMarks) values('Mike',89);
mysql> insert into DemoTable1896(StudentName,StudentMarks) values('Sam',78);使用select语句显示表中的所有记录-
mysql> select * from DemoTable1896;
这将产生以下输出-
+-----------+-------------+--------------+ | StudentId | StudentName | StudentMarks | +-----------+-------------+--------------+ | 1 | Chris | 56 | | 2 | David | 98 | | 3 | Mike | 89 | | 4 | Sam | 78 | +-----------+-------------+--------------+ 4 rows in set (0.00 sec)
这是从特定的MySQL行获取值的查询-
mysql> set @Name:=NULL; mysql> select StudentName into @Name from DemoTable1896 where StudentMarks=98;
现在您可以显示上述变量的值-
mysql> select @Name;
这将产生以下输出-
+-------+ | @Name | +-------+ | David | +-------+ 1 row in set (0.00 sec)