MySQL 查询更新每个具有相同值的替代行字符串?
mysqlmysqli database
首先我们创建一个表 −
mysql> create table DemoTable -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Subject varchar(100) -> ); Query OK, 0 rows affected (0.76 sec)
使用 insert 命令在表中插入一些记录 −
mysql> insert into DemoTable(Subject) values('C');
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable(Subject) values('MongoDB');
Query OK, 1 row affected (0.21 sec)
mysql> insert into DemoTable(Subject) values('Java');
Query OK, 1 row affected (0.18 sec)
mysql> insert into DemoTable(Subject) values('MongoDB');
Query OK, 1 row affected (0.12 sec)
mysql> insert into DemoTable(Subject) values('Python');
Query OK, 1 row affected (0.19 sec)
mysql> insert into DemoTable(Subject) values('MongoDB');
Query OK, 1 row affected (0.16 sec)
使用 select 语句显示表中的所有记录 −
mysql> select *from DemoTable;
输出
+----+---------+ | Id | Subject | +----+---------+ | 1 | C | | 2 | MongoDB | | 3 | Java | | 4 | MongoDB | | 5 | Python | | 6 | MongoDB | +----+---------+ 6 rows in set (0.00 sec)
以下是更新每隔一行字符串 − 的查询
mysql> update DemoTable set Subject=replace(Subject,'MongoDB','MySQL') where Id%2=0; Query OK, 3 rows affected (0.17 sec) Rows matched: 3 Changed: 3 Warnings: 0
让我们检查表中的所有记录 −
mysql> select *from DemoTable;
输出
+----+---------+ | Id | Subject | +----+---------+ | 1 | C | | 2 | MySQL | | 3 | Java | | 4 | MySQL | | 5 | Python | | 6 | MySQL | +----+---------+ 6 rows in set (0.00 sec)
