如何在MySQL中实现HAVING LENGTH(field)？
让我们首先创建一个表-
mysql> create table DemoTable ( Title text );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable values('Introduction to MySQL');
mysql> insert into DemoTable values('Introduction to Java');
mysql> insert into DemoTable values('Introduction to SQL');
mysql> insert into DemoTable values('Introduction to Python');
mysql> insert into DemoTable values('Introduction to SQL');
mysql> insert into DemoTable values('Introduction to Java');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 | +------------------------+ | 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)
以下是在MySQL中实现HAVINGLENGTH(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 | +----------------------+ | Introduction to SQL | | Introduction to Java | +----------------------+ 2 rows in set (0.00 sec)