删除MySQL中的最后4个字母？
您可以SUBSTRING()与UPDATE命令一起使用以删除最后4个字母。让我们首先创建一个表-
mysql> create table DemoTable ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentSubject varchar(100) );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable(StudentSubject) values('Introduction to Java');
mysql> insert into DemoTable(StudentSubject) values('Introduction to C');
mysql> insert into DemoTable(StudentSubject) values('Introduction to C++');
mysql> insert into DemoTable(StudentSubject) values('Spring And Hibernate');以下是使用select语句显示表中所有记录的查询-
mysql> select *from DemoTable;
这将产生以下输出-
+-----------+----------------------+ | StudentId | StudentSubject | +-----------+----------------------+ | 1 | Introduction to Java | | 2 | Introduction to C | | 3 | Introduction to C++ | | 4 | Spring And Hibernate | +-----------+----------------------+ 4 rows in set (0.00 sec)
以下是删除最后4个字母的查询-
mysql> update DemoTable set StudentSubject=SUBSTRING(StudentSubject, 1, LENGTH(StudentSubject)-4) ; Rows matched: 4 Changed: 4 Warnings: 0
让我们显示表中的所有记录以检查最后4个字母是否已删除-
mysql> select *from DemoTable;
这将产生以下输出-
+-----------+------------------+ | StudentId | StudentSubject | +-----------+------------------+ | 1 | Introduction to | | 2 | Introduction | | 3 | Introduction to | | 4 | Spring And Hiber | +-----------+------------------+ 4 rows in set (0.00 sec)
是的，最近4个字母已成功删除。