MySQL 查询显示空列的自定义文本
mysqlmysqli database更新于 2024/8/9 6:36:17
首先我们创建一个表 −
mysql> create table DemoTable -> ( -> FirstName varchar(20) -> ); Query OK, 0 rows affected (0.77 sec)
使用 insert 命令在表中插入一些记录 −
mysql> insert into DemoTable values('Chris');
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable values('');
Query OK, 1 row affected (0.16 sec)
mysql> insert into DemoTable values('David');
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable values('Bob');
Query OK, 1 row affected (0.15 sec)
mysql> insert into DemoTable values('');
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 −
+-----------+ | FirstName | +-----------+ | Chris | | | | David | | Bob | | | +-----------+ 5 rows in set (0.00 sec)
以下是显示空列的自定义文本的查询 −
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)
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mysql 参考教程 - 该教程包含有关 mysql 的更多信息:https://www.cainiaomax.com/mysql/
