MySQL Function

MyFreeIT2025-09-06 12:16

DATE_SUB

subtracting days

sql 复制代码

SELECT DATE_SUB('2025-09-05', INTERVAL 7 DAY);
-- Result: '2025-08-29'

SELECT DATE_SUB('2025-09-05', INTERVAL 3 MONTH);
-- Result: '2025-06-05'

SELECT DATE_SUB('2025-09-05', INTERVAL 1 YEAR);
-- Result: '2024-09-05'

SELECT DATE_SUB('2025-09-05 10:30:00', INTERVAL '2:15' HOUR_MINUTE);
-- Result: '2025-09-05 08:15:00'

WEEK(date , firstdayofweek) 周

Optional. Specifies what day the week starts on. Can be one of the following:

0 - First day of week is Sunday

1 - First day of week is Monday and the first week of the year has more than 3 days

2 - First day of week is Sunday

3 - First day of week is Monday and the first week of the year has more than 3 days

4 - First day of week is Sunday and the first week of the year has more than 3 days

5 - First day of week is Monday

6 - First day of week is Sunday and the first week of the year has more than 3 days

7 - First day of week is Monday

日期是第几周

sql 复制代码

SELECT WEEK('2025-06-02 10:08:29', 2 ) - WEEK(DATE_SUB('2025-06-02 10:08:29', 
INTERVAL DAYOFMONTH('2025-06-02 10:08:29') - 1 DAY), 2 )+1 AS week_of_month;

SELECT WEEK('2025-06-30 10:08:29', 2 ) - WEEK(DATE_SUB('2025-06-30 10:08:29', 
INTERVAL DAYOFMONTH('2025-06-30 10:08:29') - 1 DAY), 2 )+1 AS week_of_month;



SELECT WEEK ( '2025-06-02 10:46:46', 2 ) - 
WEEK ( DATE_FORMAT( '2025-06-02 10:46:46', '%Y-%m-01' ), 2 )+1

SELECT WEEK ( '2025-06-30 10:46:46', 2 ) - WEEK ( 
DATE_FORMAT( '2025-06-30 10:46:46', '%Y-%m-01' ), 2 )+1