Question

考虑两个（或更多）查询的UNION：

    SELECT activity AS activity1, completion AS status1, date_end AS date1
    FROM activities
    WHERE (
        matter LIKE '%JR161167' 
        AND activity LIKE '1.1 %' 
        AND DATEDIFF( CURDATE( ) , date_end ) <120 
    )
UNION
    SELECT activity AS activity2, completion AS status2, date_end AS date2
    FROM activities
    WHERE (
        matter LIKE '%JR161167' 
        AND activity LIKE '1.2 %' 
        AND DATEDIFF( CURDATE( ) , date_end ) <120 
    )

活动列将包含变量字符串值，但该字符串将可靠地添加到1.1或1.2或1.3一直到1.9。

问题列也是一个字符串，但会可靠地附加一个类似于JR161167的帐号。

我想查询过去120天内具有date_end的所有记录（即DATEFIFF部分），与指定的帐号（JR161167）匹配，但活动字段包含任何和所有子字符串“1 名词的”。

使用UNION从单个表“活动”返回正确的数据，但似乎没有办法在第一个查询的列或别名下标题结果集。相反，我想要像：

activity1             status1    date1     activity2 status2          date2
--------------------------------------------------------------------------------
1.1 Step 1 begins...  Incomplete 2017-4-16 1.2       Step 2 begins... Incomplete 2017-4-30

相反，我的查询在一个别名列标题activity1下堆叠所有结果，无论它们是否包含1.1,1.2,1.3等。与日期和完成字段数据相同，它不会很好地排序到相应的date1，date2等，或status1，status2等。

我最近读了一个看起来像这样的例子，它看起来像我想要实现的逻辑，我想知道是否有人能理解它的意图并帮助我制定正确的查询：

SELECT date_end
IF( WHERE description LIKE '1.1 %') AS date1,
IF( WHERE description LIKE '1.2 %') AS date2`
FROM activities

Answer 1

here

查询1 ：

SELECT a1.*, a2.*
FROM (
    SELECT matter, activity, completion, date_end
    FROM activities
    WHERE 
        matter LIKE '%JR16116' 
        AND activity = '1.1' 
        AND DATEDIFF(CURDATE(), date_end) <120
) a1
JOIN (
    SELECT matter, activity, completion, date_end
    FROM activities
    WHERE 
        matter LIKE '%JR16116' 
        AND activity = '1.2' 
        AND DATEDIFF(CURDATE(), date_end) <120
) a2
    ON a1.matter = a2.matter

<强> SQL Fiddle ：

|  matter | activity | completion |   date_end |  matter | activity | completion |   date_end |
|---------|----------|------------|------------|---------|----------|------------|------------|
| JR16116 |      1.1 |          1 | 2017-04-22 | JR16116 |      1.2 |          1 | 2017-04-23 |

查询2 ：

    -- other way without sub request but clean join

SELECT 
    a.matter, a.activity, a.completion, a.date_end
    ,a2.activity, a2.completion, a2.date_end
    -- ,a3.activity, a3.completion, a3.date_end
FROM activities a
JOIN activities a2
    ON (
        a.matter = a2.matter
        AND a2.activity = '1.2' 
        AND DATEDIFF(CURDATE(), a2.date_end) <120
    )
-- JOIN activities a3
--  ON (
--      a.matter = a3.matter
--      AND a3.activity = '1.3' 
--      AND DATEDIFF(CURDATE(), a3.date_end) <120
--  )

WHERE 
    a.matter LIKE '%JR16116' 
    AND a.activity = '1.1' 
    AND DATEDIFF(CURDATE(), a.date_end) <120

<强> Results ：

|  matter | activity | completion |   date_end | activity | completion |   date_end |
|---------|----------|------------|------------|----------|------------|------------|
| JR16116 |      1.1 |          1 | 2017-04-22 |      1.2 |          1 | 2017-04-23 |

需要像UNION这样的查询，但返回第2和第n个查询的相应列别名中的数据，而不是第一个查询列/别名

1 个答案: