丢弃MySQL中字段的最后3个字符
让我们首先创建一个表-
create table DemoTable -> ( -> StudentId varchar(100) -> );
使用插入命令在表中插入一些记录-
insert into DemoTable values('STU-090');
insert into DemoTable values('STU-123');
insert into DemoTable values('STU-678');使用select语句显示表中的所有记录-
select *from DemoTable;
输出结果
这将产生以下输出-
+-----------+ | StudentId | +-----------+ | STU-090 | | STU-123 | | STU-678 | +-----------+ 3 rows in set (0.00 sec)
以下是丢弃字段的后3个字符的查询-
SELECT REVERSE(SUBSTR(REVERSE(StudentId), 4)) from DemoTable
输出结果
这将产生以下输出-
+----------------------------------------+ | REVERSE(SUBSTR(REVERSE(StudentId), 4)) | +----------------------------------------+ | STU- | | STU- | | STU- | +----------------------------------------+ 3 rows in set (0.00 sec)