MySQL 如何比较时间戳

要在MySQL中比较时间戳，可以使用DATE()函数。让我们先创建一个表-

mysql> create table comparingTimestampDemo
   -> (
   -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   -> AdmissionDate timestamp
   -> );
Query OK, 0 rows affected (0.54 sec)

以下是使用insert命令将记录插入到表中的查询-

mysql> insert into comparingTimestampDemo(AdmissionDate) values('2019-03-31');
Query OK, 1 row affected (0.13 sec)
mysql> insert into comparingTimestampDemo(AdmissionDate) values('2019-04-10');
Query OK, 1 row affected (0.12 sec)
mysql> insert into comparingTimestampDemo(AdmissionDate) values('2019-04-15');
Query OK, 1 row affected (0.17 sec)
mysql> insert into comparingTimestampDemo(AdmissionDate) values('2019-03-29');
Query OK, 1 row affected (0.15 sec)
mysql> insert into comparingTimestampDemo(AdmissionDate) values('2019-04-07');
Query OK, 1 row affected (0.18 sec)

以下是使用select语句从表中显示所有记录的查询-

mysql> select * from comparingTimestampDemo;

这将产生如下输出-

+----+---------------------+
| Id | AdmissionDate       |
+----+---------------------+
| 1  | 2019-03-31 00:00:00 |
| 2  | 2019-04-10 00:00:00 |
| 3  | 2019-04-15 00:00:00 |
| 4  | 2019-03-29 00:00:00 |
| 5  | 2019-04-07 00:00:00 |
+----+---------------------+
5 rows in set (0.00 sec)

现在让我们在MySQL中比较时间戳-

mysql> SELECT DATE(`AdmissionDate`) FROM comparingTimestampDemo WHERE
DATE(`AdmissionDate`) < CURDATE() - INTERVAL 3 DAY;

这将产生如下输出-

+-----------------------+
| DATE(`AdmissionDate`) |
+-----------------------+
| 2019-03-31            |
| 2019-03-29            |
+-----------------------+
2 rows in set (0.00 sec)

阅读更多：MySQL 教程