MySQL 如何实现HAVING LENGTH(field)

首先创建一个表 –

mysql> create table DemoTable
(
   Title text
);
Query OK, 0 rows affected (0.39 sec)

使用insert命令向表中插入一些记录 –

mysql> insert into DemoTable values('MySQL入门');
Query OK, 1 row affected (0.11 sec)
mysql> insert into DemoTable values('Java入门');
Query OK, 1 row affected (0.09 sec)
mysql> insert into DemoTable values('SQL入门');
Query OK, 1 row affected (0.10 sec)
mysql> insert into DemoTable values('Python入门');
Query OK, 1 row affected (0.10 sec)
mysql> insert into DemoTable values('SQL入门');
Query OK, 1 row affected (0.09 sec)
mysql> insert into DemoTable values('Java入门');
Query OK, 1 row affected (0.13 sec)

使用select语句显示表中的所有记录 –

mysql> select *from DemoTable;

这将产生以下输出 –

+------------------------+
| Title                  |
+------------------------+
| MySQL入门              |
| Java入门               |
| SQL入门                |
| Python入门             |
| SQL入门                |
| Java入门               |
+------------------------+
6 rows in set (0.00 sec)

以下是在MySQL中实现HAVING LENGTH(field)的查询 –

mysql> select *from DemoTable group by length(Title)
   having length(Title) < 21;

这将产生以下输出 –

+----------------------+
| Title                |
+----------------------+
| SQL入门              |
| Java入门             |
+----------------------+
2 rows in set (0.00 sec)

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