如何在 MySQL 中实现 HAVING LENGTH(field)？

我们先创建一个表 -

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

这将生成以下输出 -

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

以下查询就是在 MySQL 中实现 HAVING LENGTH(field) -

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

这将生成以下输出 -

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

AmitDiwan

更新于：2019-9-24

102 次浏览

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