Question

我必须编写一个在2行之间搜索的查询，但只匹配两行中的值。我搜索的数据是一个包含名字和姓氏的表是单独的行。不要告诉我，我应该把它们存放在同一行。我不能，这就是需要说的。我需要做的是有一个组合记录的查询，以便我可以在不同的列中搜索它们。

数据格式如下：

StudentValues
    ID
    StudentID
    FieldID
    Response

fieldid为1给出了响应列中的第一个名称，fieldid为2给出了响应列中的姓氏，StudentID将用于对记录进行分组。

我已经能够构建以下SQL但where子句现在失败

    SELECT StudentId, MIN(CASE WHEN FieldId = 1 THEN Response ELSE NULL END) AS fname, MIN(CASE WHEN FieldId = 2 THEN Response ELSE NULL END) AS lname
    FROM sms_studentvalues
    WHERE fname = 'Some Value'
      AND lname = 'Some Value'
    GROUP BY studentid

Answer 1

在评论后更新

SELECT *
FROM (
    SELECT  StudentId,
            MIN(CASE WHEN FieldId = 1 THEN Response ELSE NULL END) AS Name, 
            MIN(CASE WHEN FieldId = 2 THEN Response ELSE NULL END) AS LastName
    FROM YourTable
    GROUP BY StudentId) AS StudentsNames
WHERE Name = 'Some Value' AND LastName = 'Some Value'

Answer 2

你有没有想过在FieldID上使用PIVOT？这将允许您在同一查询中同时提取名字和姓氏（FieldID = 1，FieldID = 2）。

Answer 3

SELECT *
FROM StudentValues s1 JOIN StudentValues s2 ON
  s1.StudentID = s2.StudentID
WHERE
  s1.FieldID = 1 AND s1.Response = 'Larry' AND
  s2.FieldID = 2 AND s2.Response = 'Ellison'

Answer 4

SELECT a.ID, a.StudentID, a.Response, b.Response
FROM StudentValues a
INNER JOIN StudentValues B ON a.ID=b.ID and b.FieldID=2
WHERE a.FieldID=1

Answer 5

联接可以这样做：

SELECT
    svf.Response AS FirstName,
    svl.Response AS LastName
FROM StudentValues svf
    INNER JOIN StudentValues svl ON svf.StudentID = svl.StudentID
        AND svl.FieldID = 2
WHERE svf.FieldID = 1

在查询中组合记录

5 个答案: