sql - 在 SQL SERVER 2008 中结合静态列和动态列

Question

我有一个包含三列和以下值的表 SchoolStudent

现在，对于学生，我们可以将动态列存储在表中，其值为：

我想要一个查询，我可以在单个 SQL 查询中包含静态字段和动态字段。我尝试使用 Pivot 但没有成功。请就如何实现这一点提出建议。我基本上这样做是为了在前端我有一个可以通过搜索的结果集。

所以查询应该是：

Select 
    StudentID, FirstName, Address, MotherName, 
    MotherEmail, MotherOccupation, Mother Salary, 
    FacebookProfileName, VehicleRegNo 
from SchoolStudent 
Inner Join 
    (Logic to convert rows to columns)

Answer 1

由于您有动态列，因此您将需要使用动态 SQL 来生成您想要的结果。此查询将生成第二个表中的列列表并将它们 PIVOT 然后连接到SchoolStudent以获取其他列：

DECLARE @cols AS NVARCHAR(MAX),
    @query  AS NVARCHAR(MAX)

select @cols = STUFF((SELECT distinct ',' + QUOTENAME(DynamicColumnName) 
                    from StudentDetails
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

set @query = '
         select s.studentid,
            s.firstname,
            s.address,
            d.*
         from SchoolStudent s
         inner join 
         (
            SELECT studentId,' + @cols + ' 
            from 
            (
                select studentId, dynamiccolumnname, 
                  dynamiccolumnvalue
                from StudentDetails
            ) x
            pivot 
            (
                max(dynamiccolumnvalue)
                for dynamiccolumnname in (' + @cols + ')
            ) p 
          ) d
            on s.StudentId = d.StudentId'

execute(@query);

请参阅SQL Fiddle with Demo。此查询给出结果：

| STUDENTID | FIRSTNAME |   ADDRESS | FACEBOOK PROFILE NAME | MOTHER EMAIL | MOTHER NAME | MOTHER OCCUPATION | MOTHER SALARY | VEHICLE REG NO |
-----------------------------------------------------------------------------------------------------------------------------------------------
|         4 |     admin | efewfwfew |                  ross |  ram@ram.com | ram@ram.com |       ram@ram.com |   ram@ram.com |       UP 14 as |

Answer 2

您可以使用这样的子查询格式：

SELECT t1.StudentID, 
       t1.FirstName, 
       t1.Address, 
       (SELECT t2.DynamicColumnValue FROM table2 t2 WHERE t2.StudentID = t1.StudentID AND t2.DynamicColumnName = 'Mother Name') AS 'MotherName',
       (SELECT t2.DynamicColumnValue FROM table2 t2 WHERE t2.StudentID = t1.StudentID AND t2.DynamicColumnName = 'Mother Email') AS 'MotherEmail'
FROM Table1 t1

或者您可以像这样使用内部连接格式：

SELECT t1.StudentID, 
       t1.FirstName, 
       t1.Address,
       t2.DynamicColumnValue AS 'MotherName'
       t3.DynamicColumnValue AS 'MotherEmail'
FROM Table1 t1
INNER JOIN Table2 t2 ON t1.StudentID = t2.StudentID AND t2.DynamicColumnName = 'Mother Name'
INNER JOIN Table2 t3 ON t1.StudentID = t3.StudentID AND t2.DynamicColumnName = 'Mother Email'

Answer 3

使用一些动态 sql，您可以这样做：

DECLARE @cols NVARCHAR(2000)
SELECT  @cols = STUFF((SELECT DISTINCT '],[' + DynamicColumnName FROM DynamicValues ORDER BY '],[' + DynamicColumnName FOR XML PATH('')), 1, 2, '') + ']'

DECLARE @query NVARCHAR(4000);
SET @query = N'select s.StudentID, s.FirstName, s.Address,'+@cols+' from SchoolStudent s
join
(
    select * from DynamicValues
    pivot (Max(DynamicColumnValue) for DynamicColumnName in ('+@cols+')) as pvt
) as b on b.StudentID=s.StudentID'
EXECUTE(@query)