MySQL查询以显示空列的自定义文本
让我们首先创建一个表-
mysql> create table DemoTable -> ( -> FirstName varchar(20) -> );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable values('Chris');
mysql> insert into DemoTable values('');
mysql> insert into DemoTable values('David');
mysql> insert into DemoTable values('Bob');
mysql> insert into DemoTable values('');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-
+-----------+ | FirstName | +-----------+ | Chris | | | | David | | Bob | | | +-----------+ 5 rows in set (0.00 sec)
以下是查询以显示空列的自定义文本-
mysql> select if(FirstName='','Not Applicable',FirstName) as Status from DemoTable;
这将产生以下输出-
+----------------+ | Status | +----------------+ | Chris | | Not Applicable | | David | | Bob | | Not Applicable | +----------------+ 5 rows in set (0.00 sec)