十一、一些有用的SQL查询语句

1、 将一个表的一些字段插入到另一个表中。

Insert Into 表1（表1字段1，表1字段2） Selecet 表2字段1，表2字段2  from 表2

INSERT INTO Tongji

                   (TongjiMajorID, TongjiMajorSumScore, TongjiMajorPerson)

SELECT  ReviewMajorID, AVG(ReviewSumScore) AS Expr1, COUNT(*) AS Expr2

FROM      tbReview

GROUP BY ReviewMajorID

2、 在一个表增加一个另一个表的字段

第一种方法：update 表1 set 表1的字段=表2的字段 from 表1，表2 where 表1的字段=表2的字段

update Tongji set TongjiMajorName =MajorName,TongjiDepartmentID=MajorDepartmentID   from Tongji,tbMajor where TongjiMajorID=MajorID

update Tongji  set TongjiDepartmentName =DepartmentName from Tongji,tbDepartment where TongjiDepartmentID=DepartmentID

第二种方法：update 表1 set表1的字段=表2的字段 from 表1 INNER JOIN 表1 on 表1字段1=表2字段1

UPDATE  Tongji

SET           TongjiDepartmentName = tbDepartment.DepartmentName

FROM      Tongji INNER JOIN

                   tbDepartment ON Tongji.TongjiDepartmentID = tbDepartment.DepartmentID CROSS JOIN

                   Tongji AS Tongji_1

最近做了个小项目，留在这里以后备查。

最后的统计用的查询，当然以也可以写成存储过程：

正确的查询1：

INSERT INTO tbMerger

                   (MergerMajorID, MergerMajorName, MergerDepartmentID)

SELECT  MajorID, MajorName, MajorDepartmentID

FROM      tbMajor

 

2:

UPDATE  tbMerger

SET           MergerReviewSumScore = Tongji.TongjiMajorSumScore, MergerReviewPerson = Tongji.TongjiMajorPerson

FROM      Tongji INNER JOIN

                   tbMerger ON Tongji.TongjiMajorID = tbMerger.MergerMajorID

 

3:

UPDATE  tbMerger

SET           MergerJwcSumScore = tbJwcReview.JwcReviewSumScore

FROM      tbJwcReview INNER JOIN

                   tbMerger ON tbJwcReview.JwcReviewMajorID = tbMerger.MergerMajorID

 

4、UPDATE  tbMerger

SET           MergerDepartmentName = tbDepartment.DepartmentName

FROM      tbDepartment INNER JOIN

                   tbMerger ON tbDepartment.DepartmentID = tbMerger.MergerDepartmentID

 

5、UPDATE  tbMerger

SET           MergerTotalMajorScore = MergerReviewSumScore + MergerJwcSumScore

 

6、update tbMerger set MergerDateTime='"+DateTime.Now+"'