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从MySQL中具有DATE和NULL记录的表中过滤日期

2024-04-29 21:55:06 441

让我们首先创建一个表-

mysql> create table DemoTable
(
   FirstDate datetime,
   SecondDate datetime
);

使用插入命令在表中插入一些记录-

mysql> insert into DemoTable values('2019-01-21','2018-01-21');
mysql> insert into DemoTable values('2019-10-04','2019-08-14');
mysql> insert into DemoTable values('2019-05-01','2019-09-11');
mysql> insert into DemoTable values(NULL,NULL);
mysql> insert into DemoTable values('2019-03-01',NULL);

使用select语句显示表中的所有记录-

Display all records from the table using select statement:

这将产生以下输出-

+---------------------+---------------------+
| FirstDate           | SecondDate          |
+---------------------+---------------------+
| 2019-01-21 00:00:00 | 2018-01-21 00:00:00 |
| 2019-10-04 00:00:00 | 2019-08-14 00:00:00 |
| 2019-05-01 00:00:00 | 2019-09-11 00:00:00 |
| NULL                | NULL                |
| 2019-03-01 00:00:00 | NULL                |
+---------------------+---------------------+
5 rows in set (0.00 sec)

以下是从具有DATE和NULL记录的表中过滤日期的查询-

mysql> select *from DemoTable
where FirstDate <= curdate() and (SecondDate >=curdate() or SecondDate IS NULL);

这将产生以下输出-

+---------------------+---------------------+
| FirstDate           | SecondDate          |
+---------------------+---------------------+
| 2019-05-01 00:00:00 | 2019-09-11 00:00:00 |
| 2019-03-01 00:00:00 | NULL                |
+---------------------+---------------------+
2 rows in set (0.00 sec)

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从MySQL中具有DATE和NULL记录的表中过滤日期

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