1.dayofweek函數

功能：統計某天為星期幾

dayofweek(date) - Returns the day of the week for date/timestamp (1 = Sunday, 2 = Monday, ..., 7 = Saturday).

dayofweek返回值為：1-7，1 = 星期日, 2 = 星期一, …, 7 = 星期六，從星期日開始

示例：

SELECT dayofweek('2025-07-15');  ---3(星期二)

2.weekday函數

功能：統計某天為星期幾

weekday(date) - Returns the day of the week for date/timestamp (0 = Monday, 1 = Tuesday, ..., 6 = Sunday).

weekday返回值為：0-6，0 = 星期一, 1 = 星期二, …, 6= 星期日，從星期一開始
示例：

select weekday('2025-07-15');  ---1(星期二)

3.weekofyear函數

功能統計：某天為某年的第幾周

weekofyear(date) - Returns the week of the year of the given date. A week is considered to start on a Monday and week 1 is the first week with >3 days.

select weekofyear('2025-07-15') --29