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MySQL CASE何时使用SELECT显示奇数和偶数id？

2024-05-13 10:49:05 357

让我们首先创建一个表-

mysql> create table DemoTable
(
   PageId int
);

使用插入命令在表中插入一些记录-

mysql> insert into DemoTable values(233);
mysql> insert into DemoTable values(34);
mysql> insert into DemoTable values(76);
mysql> insert into DemoTable values(89);

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-

+--------+
| PageId |
+--------+
|    233 |
|     34 |
|     76 |
|     89 |
+--------+
4 rows in set (0.00 sec)

以下是带有SELECT的CASEWHEN的查询-

mysql> select PageId, case when PageId %2 !=0 then 'PageId is odd' else 'PageId is even' end AS Result from DemoTable;

这将产生以下输出-

+--------+----------------+
| PageId | Result         |
+--------+----------------+
|    233 |  PageId is odd |
|     34 |  PageId is even|
|     76 |  PageId is even|
|     89 |   PageId is odd|
+--------+----------------+
4 rows in set (0.00 sec)

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MySQL CASE何时使用SELECT显示奇数和偶数id？

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