Transform Dates into Date Range in MYSQL---如何处理日期间隔

Question

我正在寻求将以下数据转换为所需输出的帮助。我们有 Item,LOC DAY 级别的数据，需要将其转换为 Item,Loc Date Range 以减少 table 中的记录数并满足其他要求。

Item        LOC  RP_DATE    RP_IND   
1003785256  543 2016-11-05  Y
1003785256  543 2016-11-06  Y
1003785256  543 2016-11-07  Y
1003785256  543 2016-11-09  Y
1003785256  543 2016-11-10  Y
1003790365  150 2016-11-05  Y
1003797790  224 2016-11-05  Y
1003797790  224 2016-11-06  Y
1003797790  224 2016-11-07  Y
1003797790  224 2016-11-08  Y

所需输出：

Item        LOC  RP_ST_DATE    RP_END_DATE   
1003785256  543 2016-11-05   2016-11-07
1003785256  543 2016-11-09   2016-11-10
1003790365  150 2016-11-05   2016-11-05
1003797790  224 2016-11-05   2016-11-08

Answer 1

此方法适用于 MySQL。它在有序子查询中使用组合变量来为每个 "range" 建立一个共同的开始日期。 CROSS JOIN 仅用于初始化变量，它不会改变行数。一旦建立了共同的开始日期，它就变成了外部查询中的一个简单的分组查询。

SELECT Item, LOC, RP_IND, dr_begin, MAX(RP_DATE) dr_end
FROM (
  SELECT
         mytable.*
       , @fin := CONVERT(IF(@item<=>item AND @loc<=>loc AND DATEDIFF(rp_date, @d)=1, @fin, rp_date), DATE) AS dr_begin
       , @item := item
       , @loc := loc
       , @d := rp_date
  FROM     mytable CROSS JOIN (SELECT @item:=NULL, @loc:=NULL, @d:=NULL, @fin := NULL) AS init
  ORDER BY item, loc, rp_date
  ) d
GROUP BY  Item, LOC, RP_IND, dr_begin
;

+----+------------+-----+--------+------------+---------------------+
|    |    Item    | LOC | RP_IND |  dr_begin  |       dr_end        |
+----+------------+-----+--------+------------+---------------------+
|  1 | 1003785256 | 543 | Y      | 2016-11-05 | 07.11.2016 00:00:00 |
|  2 | 1003785256 | 543 | Y      | 2016-11-09 | 10.11.2016 00:00:00 |
|  3 | 1003790365 | 150 | Y      | 2016-11-05 | 05.11.2016 00:00:00 |
|  4 | 1003797790 | 224 | Y      | 2016-11-05 | 08.11.2016 00:00:00 |
+----+------------+-----+--------+------------+---------------------+

备注<=>returns 1 if both operands are NULL

查看查询工作于：http://rextester.com/SEYG96251

#drop table mytable;

CREATE TABLE mytable(
   Item    INTEGER  NOT NULL
  ,LOC     INTEGER  NOT NULL
  ,RP_DATE DATE  NOT NULL
  ,RP_IND  VARCHAR(1) NOT NULL
);
INSERT INTO mytable(Item,LOC,RP_DATE,RP_IND) VALUES (1003785256,543,'2016-11-05','Y');
INSERT INTO mytable(Item,LOC,RP_DATE,RP_IND) VALUES (1003785256,543,'2016-11-06','Y');
INSERT INTO mytable(Item,LOC,RP_DATE,RP_IND) VALUES (1003785256,543,'2016-11-07','Y');
INSERT INTO mytable(Item,LOC,RP_DATE,RP_IND) VALUES (1003785256,543,'2016-11-09','Y');
INSERT INTO mytable(Item,LOC,RP_DATE,RP_IND) VALUES (1003785256,543,'2016-11-10','Y');
INSERT INTO mytable(Item,LOC,RP_DATE,RP_IND) VALUES (1003790365,150,'2016-11-05','Y');
INSERT INTO mytable(Item,LOC,RP_DATE,RP_IND) VALUES (1003797790,224,'2016-11-05','Y');
INSERT INTO mytable(Item,LOC,RP_DATE,RP_IND) VALUES (1003797790,224,'2016-11-06','Y');
INSERT INTO mytable(Item,LOC,RP_DATE,RP_IND) VALUES (1003797790,224,'2016-11-07','Y');
INSERT INTO mytable(Item,LOC,RP_DATE,RP_IND) VALUES (1003797790,224,'2016-11-08','Y');

Transform Dates into Date Range in MYSQL---如何处理日期间隔

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