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在MySQL中为空值和空值的单列实现两个条件

2024-05-02 05:33:04 437

让我们首先创建一个表-

mysql> create table DemoTable635(
   EmployeId int NOT NULL AUTO_INCREMENT PRIMARY KEY,EmployeeName varchar(100)
);

使用插入命令在表中插入一些记录-

mysql> insert into DemoTable635(EmployeeName) values('John');
mysql> insert into DemoTable635(EmployeeName) values('Sam');
mysql> insert into DemoTable635(EmployeeName) values('');
mysql> insert into DemoTable635(EmployeeName) values(null);
mysql> insert into DemoTable635(EmployeeName) values('David');

使用select语句显示表中的所有记录-

mysql> select *from DemoTable635;

这将产生以下输出-

+-----------+--------------+
| EmployeId | EmployeeName |
+-----------+--------------+
|         1 | John         |
|         2 | Sam          |
|         3 |              |
|         4 | NULL         |
|         5 | David        |
+-----------+--------------+
5 rows in set (0.00 sec)

以下是查询以避免显示MySQL列中的空值和空值-

mysql> select *from DemoTable635 tbl where tbl.EmployeeName is not null and tbl.EmployeeName <> '';

这将产生以下输出-

+-----------+--------------+
| EmployeId | EmployeeName |
+-----------+--------------+
|         1 | John         |
|         2 | Sam          |
|         5 | David        |
+-----------+--------------+
3 rows in set (0.02 sec)

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在MySQL中为空值和空值的单列实现两个条件

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