微客导航 » 文章资讯 » 使用MySQL SELECT进行简单的BOOLEAN评估？

使用MySQL SELECT进行简单的BOOLEAN评估？

2024-04-27 11:12:05 365

您可以为此使用CASE语句。让我们看一个例子-

mysql> create table BooleanEvaluationDemo
   -> (
   -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   -> FirstValue int,
   -> SecondValue int
   -> );

使用insert命令在表中插入一些记录。查询如下-

mysql> insert into BooleanEvaluationDemo(FirstValue,SecondValue) values(10,5);
mysql> insert into BooleanEvaluationDemo(FirstValue,SecondValue) values(15,20);
mysql> insert into BooleanEvaluationDemo(FirstValue,SecondValue) values(50,40);
mysql> insert into BooleanEvaluationDemo(FirstValue,SecondValue) values(500,1000);

使用select语句显示表中的所有记录。查询如下-

mysql> select *from BooleanEvaluationDemo;

这是输出-

+----+------------+-------------+
| Id | FirstValue | SecondValue |
+----+------------+-------------+
| 1  | 10         | 5           |
| 2  | 15         | 20          |
| 3  | 50         | 40          |
| 4  | 500        | 1000        |
+----+------------+-------------+
4 rows in set (0.00 sec)

以下是用于简单BOOLEAN评估的SELECT查询-

mysql> SELECT FirstValue,SecondValue,CASE WHEN FirstValue > SecondValue THEN
'true' ELSE 'false' END AS FirstValuesGreaterThanSecond from BooleanEvaluationDemo;

这是输出-

+------------+-------------+-------------------------------+
| FirstValue | SecondValue | FirstValuesGreaterThanSecond  |
+------------+-------------+-------------------------------+
| 10         | 5           | true                          |
| 15         | 20          | false                         |
| 50         | 40          | true                          |
| 500        | 1000        | false                         |
+------------+-------------+-------------------------------+
4 rows in set (0.00 sec)

返回顶部
3162201930
czq8825@qq.com

使用MySQL SELECT进行简单的BOOLEAN评估？

热门推荐

随机推荐