Question

如何利用MySQL函数查询特定的日期时间

Answer 1

使用 IFNULL 函数, 不知道能否满足你的需求 用法是 IFNULL ( 数据库里面的日期列, ' 如果数据库里面的日期为空，那么所使用的默认值' )mysql> create table test1( -> id int, -> test_dt date -> );Query OK, 0 rows affected (0.06 sec) mysql> insert into test1 values(1, '2014-06-17');Query OK, 1 row affected (0.03 sec) mysql> insert into test1 values(2, NULL);Query OK, 1 row affected (0.02 sec) mysql> insert into test1 values(3, '2014-07-01');Query OK, 1 row affected (0.02 sec) mysql> SELECT * FROM test1;+------+------------+| id | test_dt |+------+------------+| 1 | 2014-06-17 || 2 | NULL || 3 | 2014-07-01 |+------+------------+3 rows in set (0.00 sec) mysql> SELECT id, IFNULL(test_dt, '2014-12-31') FROM test1;+------+-------------------------------+| id | IFNULL(test_dt, '2014-12-31') |+------+-------------------------------+| 1 | 2014-06-17 || 2 | 2014-12-31 || 3 | 2014-07-01 |+------+-------------------------------+3 rows in set (0.00 sec)