数据库计算当年周六周天天数
时间: 2023-07-08 14:17:50 浏览: 43
计算当年周六周天天数,需要先了解一下什么是周六周天。通常情况下,周六和周日是周末,是非工作日。因此,可以通过查询当年内周六周日的天数来得到周末天数的次数。具体的SQL语句如下:
```
SELECT COUNT(*) AS weekends
FROM (
SELECT DATE('2022-01-01') + INTERVAL (a + (b * 10) + (c * 100)) DAY AS date
FROM (
SELECT 0 AS a UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION
SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9
) AS days0,
(
SELECT 0 AS b UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION
SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9
) AS days1,
(
SELECT 0 AS c UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION
SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9
) AS days2
WHERE DATE('2022-01-01') + INTERVAL (a + (b * 10) + (c * 100)) DAY <= '2022-12-31'
) AS days
WHERE WEEKDAY(date) IN (5, 6);
```
其中,需要将语句中的'2022-01-01'替换为当年的起始日期,'2022-12-31'替换为当年的结束日期,例如:
```
SELECT COUNT(*) AS weekends
FROM (
SELECT DATE('2021-01-01') + INTERVAL (a + (b * 10) + (c * 100)) DAY AS date
FROM (
SELECT 0 AS a UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION
SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9
) AS days0,
(
SELECT 0 AS b UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION
SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9
) AS days1,
(
SELECT 0 AS c UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION
SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9
) AS days2
WHERE DATE('2021-01-01') + INTERVAL (a + (b * 10) + (c * 100)) DAY <= '2021-12-31'
) AS days
WHERE WEEKDAY(date) IN (5, 6);
```
执行此语句后,会返回一个名为weekends的列,其中包含当年的周六周日天数,即周末天数,结果为104。