Question

我想用select语句获取两个日期之间的星期一，但我只在sql server中搜索过。

我试过这个，但它不起作用：

SELECT DATE_ADD('2017-01-01', INTERVAL ROW DAY) AS Date 
FROM (
            SELECT @row := @row + 1 AS row 
            FROM (
                        SELECT 0 UNION ALL 
                        SELECT 1 UNION ALL 
                        SELECT 3 UNION ALL 
                        SELECT 4 UNION ALL 
                        SELECT 5 UNION ALL 
                        SELECT 6
            ) t1,
            (
                SELECT 0 UNION ALL 
                SELECT 1 UNION ALL 
                SELECT 3 UNION ALL 
                SELECT 4 UNION ALL 
                SELECT 5 UNION ALL 
                SELECT 6
            ) t2, 
            (
                SELECT @row:=-1
            ) t3 LIMIT 31
        ) b
WHERE DATE_ADD('2017-01-01', INTERVAL ROW DAY) BETWEEN '2017-01-01' AND '2017-12-31'
AND DAYOFWEEK(DATE_ADD('2017-01-01', INTERVAL ROW DAY)) = 2

这个查询只给我一个月的星期一日期。

我希望你能帮助我

问候！

Answer 1

如果你真的只想解决这个SQL，你必须深入研究并生成一系列日子，这是迄今为止解决这个问题最困难的一项任务。除此之外，正如您已经猜到的那样，您可以使用DAYOFWEEK或WEEKDAY来获得所需的日期。

SELECT  * 
   FROM (
        SELECT  DATE_ADD('2013-01-01', 
            INTERVAL n4.num*1000+n3.num*100+n2.num*10+n1.num DAY ) AS DATE 
          FROM  (
              SELECT 0 AS num
              UNION ALL SELECT 1
              UNION ALL SELECT 2
              UNION ALL SELECT 3
              UNION ALL SELECT 4
              UNION ALL SELECT 5
              UNION ALL SELECT 6
              UNION ALL SELECT 7
              UNION ALL SELECT 8
              UNION ALL SELECT 9
         ) AS n1,
         (
              SELECT 0 AS num
              UNION ALL SELECT 1
              UNION ALL SELECT 2
              UNION ALL SELECT 3
              UNION ALL SELECT 4
              UNION ALL SELECT 5
              UNION ALL SELECT 6
              UNION ALL SELECT 7
              UNION ALL SELECT 8
              UNION ALL SELECT 9
        ) AS n2,
        (
              SELECT 0 AS num
              UNION ALL SELECT 1
              UNION ALL SELECT 2
              UNION ALL SELECT 3
              UNION ALL SELECT 4
              UNION ALL SELECT 5
              UNION ALL SELECT 6
              UNION ALL SELECT 7
              UNION ALL SELECT 8
              UNION ALL SELECT 9
        ) AS n3,
        (
              SELECT 0 AS num
              UNION ALL SELECT 1
              UNION ALL SELECT 2
              UNION ALL SELECT 3
              UNION ALL SELECT 4
              UNION ALL SELECT 5
              UNION ALL SELECT 6
              UNION ALL SELECT 7
              UNION ALL SELECT 8
              UNION ALL SELECT 9
        ) AS n4
    ) AS a
WHERE DATE >= '2017-01-01' AND DATE < NOW()
  AND WEEKDAY(DATE) = 0
ORDER BY DATE

其他一些RDBMS具有内置功能。</ p>

如果你有一个所有日期都已存在的日历表，那将会更容易。

Answer 2

我认为该解决方案将比以前的解决方案具有更好的性能

SET @date_start = date('2019-07-06');
SET @date_end = date('2019-09-18');

SELECT CASE WHEN MOD(DAYOFWEEK(@date_start), 7) <= 2 AND
      MOD(DAYOFWEEK(@date_start), 7) + DATEDIFF(v.selected_date, @date_start) - 7 * FLOOR(DATEDIFF(v.selected_date, @date_start) / 7) >= 2 OR
      MOD(DAYOFWEEK(@date_start), 7) > 2 AND
      MOD(DAYOFWEEK(@date_start), 7) + DATEDIFF(v.selected_date, @date_start) - 7 * FLOOR(DATEDIFF(v.selected_date, @date_start) / 7) >= 9 THEN 1 ELSE 0 END
  + FLOOR(DATEDIFF(v.selected_date, @date_start) / 7) num_of_mo
 ,  @date_start start_date,v.selected_date end_date
FROM (select adddate(@date_start,t4*10000 + t3*1000 + t2*100 + t1*10 + t0) selected_date from
 (select 0 t0 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) t0,
 (select 0 t1 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) t1,
 (select 0 t2 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) t2,
 (select 0 t3 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) t3,
 (select 0 t4 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) t4) v
WHERE v.selected_date <= @date_end;

获得两个日期之间的星期一mysql

2 个答案: