获取连续日期的集合

Question

我有一个存储员工离职的数据库。对于员工休假的每一天，都会将新记录输入到数据库中。我想要实现的是让某人输入员工 ID 和日期范围，并且对于每个缺勤期都会返回一条记录，说明日期、日期、持续时间以及是上午还是下午（半天）。

它应该看起来像（对于员工 9999 和日期 2011-08-08 到 2011-09-01）：

employee_id | Start      | start_am_pm | End        | end_am_pm | Duration
9999        | 2011-08-10 | PM          | 2011-08-12 | AM        | 2
9999        | 2011-09-01 |             | 2011-09-01 |           | 1

注意：上面的第一个持续时间是 2，因为第 10 天和第 12 天都是半天，而第 11 天是完整的。

无论如何。如果 From 日期不是员工休假的日期，我的查询完全符合我的预期。例如，在上面的示例中，如果我将起始日期设置为 10 日、11 日或 12 日，它会删除该行。它应该计算指定日期之间的天数。

当前显示方式（员工 9999 和日期 2011-08-11 至 2011-09-01）：

employee_id | Start      | start_am_pm | End        | end_am_pm | Duration
9999        | 2011-09-01 |             | 2011-09-01 |           | 1

To date 也发生了类似的情况，但我已经解决了。类似的方法不适用于 From 日期。下面是我的存储过程。

DELIMITER $$

USE `test`$$

DROP PROCEDURE IF EXISTS `GetLeaveDates`$$

CREATE DEFINER=`root`@`%` PROCEDURE `GetLeaveDates`(pEmpID INT, pDateFrom DATETIME, pDateTo DATETIME)
BEGIN

SELECT 
    a.start_date,
CASE WHEN a.am_pm = 1 THEN "AM"
     WHEN a.am_pm = 2 THEN "PM"
     ELSE "" END AS start_am_pm,
    CASE WHEN pDateTo > MIN(c.start_date) THEN
        MIN(c.start_date)
    ELSE
        pDateTo
    END AS End,
CASE WHEN c.am_pm = 1 THEN "AM"
     WHEN c.am_pm = 2 THEN "PM"
     ELSE "" END AS start_am_pm,
    CASE WHEN a.am_pm = 0 AND c.am_pm = 0 THEN
        DATEDIFF(MIN(c.start_date),a.start_date)+1
         WHEN (a.am_pm = 0 AND c.am_pm <> 0) OR (c.am_pm = 0 AND a.am_pm <> 0) THEN
        DATEDIFF(MIN(c.start_date),a.start_date)+0.5
         WHEN a.am_pm <> 0 AND c.am_pm <> 0 THEN
        DATEDIFF(MIN(c.start_date),a.start_date)
    END
     AS Duration
FROM t AS a
LEFT JOIN t AS b ON a.employee_id=b.employee_id AND a.start_date = ADDDATE(b.start_date,1)
LEFT JOIN t AS c ON a.employee_id=c.employee_id AND a.start_date <= c.start_date
LEFT JOIN t AS d ON c.employee_id=d.employee_id AND c.start_date = ADDDATE(d.start_date,-1)
WHERE b.start_date IS NULL AND c.start_date IS NOT NULL AND d.start_date IS NULL
AND a.EMPLOYEE_ID = pEmpID
AND a.START_DATE BETWEEN pDateFrom AND pDateTo
GROUP BY a.employee_id, a.start_date   
; END$$

DELIMITER ;

Answer 1

好的，我想通了，这很简单，基本上在每个LEFT JOIN 上，我都必须通过传入的参数过滤掉开始日期。

我还必须根据请假是否获得批准进行过滤，如果获得批准，请填写 Approved_DateTime 和 Approved_By 字段。在某些情况下，持续时间的计算也有点偏离。所以我的存储过程现在看起来像：

DELIMITER $$

USE `test`$$

DROP PROCEDURE IF EXISTS `GetLeaveDates`$$

CREATE DEFINER=`root`@`%` PROCEDURE `GetLeaveDates`(pEmpID INT, pDateFrom DATETIME, pDateTo DATETIME, pApproved BOOLEAN)
BEGIN

SELECT 
    DATE_FORMAT(a.start_date,'%d/%m/%y') AS start,
CASE WHEN a.am_pm = 1 THEN "AM"
     WHEN a.am_pm = 2 THEN "PM"
     ELSE "" END AS start_am_pm,
    DATE_FORMAT(CASE WHEN pDateTo > MIN(c.start_date) THEN
        MIN(c.start_date)
    ELSE
        pDateTo
    END, '%d/%m/%y') AS end,
CASE WHEN c.am_pm = 1 THEN "AM"
     WHEN c.am_pm = 2 THEN "PM"
     ELSE "" END AS end_am_pm,
  CASE WHEN a.am_pm = 0 THEN
    CASE WHEN c.am_pm = 0 OR c.am_pm = 2 THEN
        DATEDIFF(MIN(c.start_date),a.start_date)+1
    WHEN c.am_pm = 1 THEN
        DATEDIFF(MIN(c.start_date),a.start_date)+0.5
    END
WHEN a.am_pm = 1 THEN
    CASE WHEN c.am_pm = 0 OR c.am_pm = 2 THEN
        DATEDIFF(MIN(c.start_date),a.start_date)+1
    WHEN c.am_pm = 1 THEN
        DATEDIFF(MIN(c.start_date),a.start_date)+0.5
    END
WHEN a.am_pm = 2 THEN
    CASE WHEN c.am_pm = 0 OR c.am_pm = 2 THEN
        DATEDIFF(MIN(c.start_date),a.start_date)+0.5
    WHEN c.am_pm = 1 THEN
        DATEDIFF(MIN(c.start_date),a.start_date)
    END 
END AS Duration

FROM t AS a
LEFT JOIN t AS b ON a.employee_id=b.employee_id AND a.start_date = ADDDATE(b.start_date,1) AND ISNULL(b.approved_datetime) <> pApproved AND b.start_date BETWEEN pDateFrom AND pDateTo
LEFT JOIN t AS c ON a.employee_id=c.employee_id AND a.start_date <= c.start_date AND ISNULL(c.approved_datetime) <> pApproved AND c.start_date BETWEEN pDateFrom AND pDateTo
LEFT JOIN t AS d ON c.employee_id=d.employee_id AND c.start_date = ADDDATE(d.start_date,-1) AND ISNULL(d.approved_datetime) <> pApproved AND d.start_date BETWEEN pDateFrom AND pDateTo
WHERE b.start_date IS NULL AND c.start_date IS NOT NULL AND d.start_date IS NULL
AND a.EMPLOYEE_ID = pEmpID
AND a.START_DATE BETWEEN pDateFrom AND pDateTo
AND ISNULL(a.approved_datetime) <> pApproved
AND a.start_date BETWEEN pDateFrom AND pDateTo
GROUP BY a.employee_id, a.start_date
; END$$

DELIMITER ;