MySQL 查询根据条件更新不同的字段?
mysqlmysqli database更新于 2024/3/7 4:03:00
让我们首先创建一个 −
mysql> create table DemoTable1436 -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Name varchar(20) -> ); Query OK, 0 rows affected (1.06 sec)
使用 insert 在表中插入一些记录 −
mysql> insert into DemoTable1436(Name) values('Chris');
Query OK, 1 row affected (0.22 sec)
mysql> insert into DemoTable1436(Name) values('David');
Query OK, 1 row affected (0.40 sec)
mysql> insert into DemoTable1436(Name) values('Bob');
Query OK, 1 row affected (0.35 sec)
mysql> insert into DemoTable1436(Name) values('David');
Query OK, 1 row affected (0.23 sec)
mysql> insert into DemoTable1436(Name) values('David');
Query OK, 1 row affected (0.31 sec)
使用 select 语句显示表中的所有记录 −
mysql> select * from DemoTable1436;
这将产生以下输出 −
+----+-------+ | Id | Name | +----+-------+ | 1 | Chris | | 2 | David | | 3 | Bob | | 4 | David | | 5 | David | +----+-------+ 5 rows in set (0.00 sec)
以下是根据条件更新不同字段的查询 −
mysql> update DemoTable1436 -> set Name=IF(Name='David','Carol Taylor',Name) -> where Id=2; Query OK, 1 row affected (0.31 sec) Rows matched: 1 Changed: 1 Warnings: 0
让我们再次检查表记录 −
mysql> select * from DemoTable1436;
这将产生以下输出 −
+----+--------------+ | Id | Name | +----+--------------+ | 1 | Chris | | 2 | Carol Taylor | | 3 | Bob | | 4 | David | | 5 | David | +----+--------------+ 5 rows in set (0.00 sec)
