SQL 根据另一列将一列转换为两列

Question

具有以下数据集：

Extender_Record_ID: 1, 1, 2, 2, 3, 3, 4, 4, 5, 5
Field_ID: 100, 101, 100, 101, 100, 101, 100, 101, 100, 101
Date: 1/1/2018, 1/2/2018, 1/14/2018, 1/15/2018, 2/1/2018, 2/3/2018, 
      2/15/2018, 2/17/2018, 3/2/2018, 3/5/2018

我正在尝试获取以下输出：

Start Date: 1/1/2018, 1/14/2018, 2/1/2018, 2/15/2018, 3/2/2018  
End Date: 1/2/2018, 1/15/2018, 2/3/2018, 2/17/2018, 3/5/2018

我正在尝试根据 ID 列中的值将日期列拆分为两个单独的日期列。我想将其插入到更大的查询中。

抱歉，我是新手。非常感谢任何帮助！

Answer 1

很简单，一个永远是 min，另一个永远是 max，你可以这样做：

SELECT MIN(DATE) AS Date1
     , MAX(DATE) AS Date2
  FROM ...
GROUP BY ID

或者更复杂的枢轴，但我们可能需要知道 SQL 的风格

Answer 2

select extendedrecordid, field_id, max(case when field_id = 1 then date else null end )date1,
max(case when field_id = 2 then date else null end )date2
from yourtable group by extendedrecordid, field_id

Answer 3

根据您的评论 I got the min and max query to produce what i needed for the minor example.，您可能实际需要的是这样的：

SELECT 
CASE WHEN Id = 1 THEN [DateField] END AS Date1, 
CASE WHEN Id = 2 THEN [DateField] END AS Date2
FROM [MyTable]

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