MySQL 查询通过连接字符串字段来更新它?
mysqlmysqli database
要连接字符串字段，请使用 CONCAT() 函数。让我们首先创建一个表 −
mysql> create table DemoTable -> ( -> SequenceId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> StudentId varchar(100) -> ); Query OK, 0 rows affected (0.59 sec)
使用 insert 命令在表中插入一些记录 −
mysql> insert into DemoTable(StudentId) values('STU');
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable(StudentId) values('STU1');
Query OK, 1 row affected (0.18 sec)
使用 select 语句显示表中的所有记录 −
mysql> select *from DemoTable;
输出
+------------+-----------+ | SequenceId | StudentId | +------------+-----------+ | 1 | STU | | 2 | STU1 | +------------+-----------+ 2 rows in set (0.00 sec)
以下是通过连接到字符串字段 − 来更新字符串字段的查询
mysql> update DemoTable -> set StudentId=concat(StudentId,'-','101'); Query OK, 2 rows affected (0.14 sec) Rows matched: 2 Changed: 2 Warnings: 0
让我们再次检查表中的所有记录 −
mysql> select *from DemoTable;
输出
+------------+-----------+ | SequenceId | StudentId | +------------+-----------+ | 1 | STU-101 | | 2 | STU1-101 | +------------+-----------+ 2 rows in set (0.00 sec)
