在MySQL中删除最后4个字符？

您可以使用UPDATE命令和SUBSTRING()来删除最后4个字符。首先，让我们创建一个表 –

mysql> create table DemoTable
(
    StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,
    StudentSubject varchar(100)
);
Query OK, 0 rows affected (0.57 sec)

使用insert命令将一些记录插入表中 –

mysql> insert into DemoTable(StudentSubject) values('Introduction to Java');
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable(StudentSubject) values('Introduction to C');
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable(StudentSubject) values('Introduction to C++');
Query OK, 1 row affected (0.11 sec)
mysql> insert into DemoTable(StudentSubject) values('Spring And Hibernate');
Query OK, 1 row affected (0.13 sec)

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个字符的查询 –

mysql> update DemoTable set StudentSubject=SUBSTRING(StudentSubject, 1, LENGTH(StudentSubject)-4) ;
Query OK, 4 rows affected (0.16 sec)
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个字符是否已删除 –

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)