一. TIMESTAMPDIFF函数

语法:

TIMESTAMPDIFF(unit,datetime_expr1,datetime_expr2)

参数:

unit 单位( second 秒
			minute 分钟
			hour 小时
			day 天
			week 周
			month 月
			year 年)
datetime_expr1,datetime_expr2  两个时间(后者减去前者)

示例:

SELECT TIMESTAMPDIFF(SECOND,'2022-06-17 00:00:00','2022-06-17 23:59:59'); 
# 结果 = 86399秒
SELECT TIMESTAMPDIFF(MINUTE,'2022-06-17 00:00:00','2022-06-17 23:59:59');
# 结果 = 1439分钟
SELECT TIMESTAMPDIFF(HOUR,'2022-06-17 00:00:00','2022-06-17 23:59:59');
# 结果 = 23小时
SELECT TIMESTAMPDIFF(DAY,'2022-06-17 00:00:00','2022-06-17 23:59:59');
# 结果 = 0天
SELECT TIMESTAMPDIFF(WEEK,'2022-06-17 00:00:00','2022-06-17 23:59:59');
# 结果 = 0周
SELECT TIMESTAMPDIFF(MONTH,'2022-06-17 00:00:00','2022-06-17 23:59:59');
# 结果 = 0月
SELECT TIMESTAMPDIFF(YEAR,'2022-06-17 00:00:00','2022-06-17 23:59:59');
# 结果 = 0年


# 可以结合日期函数进行搭配使用
SELECT TIMESTAMPDIFF(SECOND,'2022-06-17', CURRENT_DATE());
SELECT TIMESTAMPDIFF(SECOND,'2022-06-17 00:00:00',NOW());
SELECT TIMESTAMPDIFF(SECOND,'2022-06-17 00:00:00',CURRENT_TIMESTAMP());
 
# 补充说明
SELECT CURRENT_DATE();
# 结果 = 2022-06-17
 
SELECT NOW();
# 结果 = 2022-06-17 23:55:55
 
SELECT CURRENT_TIMESTAMP();
# 结果 = 2022-06-17 23:55:55