SQL 行列转换应用

准备测试表和测试数据：

   1: CREATE TABLE [dbo].[StateLog](

   2:     [ID] [int] IDENTITY(1,1) NOT NULL,

   3:     [State] [int] NULL,

   4:     [CreateDate] [datetime] NULL

   5: ) ON [PRIMARY]

   6:  

   7: GO

   8:  

   9: INSERT INTO [dbo].[StateLog]([State],[CreateDate]) VALUES ('0','2012-03-05')

  10: INSERT INTO [dbo].[StateLog]([State],[CreateDate]) VALUES ('2','2012-03-05')

  11: INSERT INTO [dbo].[StateLog]([State],[CreateDate]) VALUES ('3','2012-03-05')

  12: INSERT INTO [dbo].[StateLog]([State],[CreateDate]) VALUES ('1','2012-03-05')

  13: INSERT INTO [dbo].[StateLog]([State],[CreateDate]) VALUES ('1','2012-03-05')

  14: INSERT INTO [dbo].[StateLog]([State],[CreateDate]) VALUES ('1','2012-03-05')

  15: INSERT INTO [dbo].[StateLog]([State],[CreateDate]) VALUES ('1','2012-03-06')

  16: INSERT INTO [dbo].[StateLog]([State],[CreateDate]) VALUES ('2','2012-03-06')

  17: INSERT INTO [dbo].[StateLog]([State],[CreateDate]) VALUES ('2','2012-03-06')

  18: INSERT INTO [dbo].[StateLog]([State],[CreateDate]) VALUES ('2','2012-03-06')

需要统计每天的总数以及各个状态有多少数量：

 

SQL语句如下：

   1: select A.CreateDate,B.TotalQty,A.State0,A.State1,A.State2,A.State3 from 

   2: (

   3:     --行列转换，核心

   4:     SELECT [0][State0],[1][State1],[2][State2],[3][State3],CreateDate FROM 

   5:     (

   6:         SELECT MAIN.[State],[StateLog].CreateDate 

   7:         FROM [StateLog] MAIN JOIN [StateLog] ON MAIN.CreateDate=[StateLog].CreateDate

   8:         WHERE MAIN.[State] IN (0,1,2,3) 

   9:             AND [StateLog].[State] IN (0,1,2,3) 

  10:             AND MAIN.[State]<>[StateLog].[State]

  11:         GROUP BY MAIN.ID,MAIN.[State],[StateLog].CreateDate

  12:     ) G

  13:     PIVOT

  14:     (

  15:         COUNT([State]) 

  16:         FOR [State] IN ([0],[1],[2],[3])

  17:     )P

  18: ) A,

  19: (

  20:     --计算总数

  21:     SELECT COUNT(1) as TotalQty, CreateDate

  22:     FROM [dbo].[StateLog]

  23:     group by CreateDate

  24: ) B

  25: where A.CreateDate=B.CreateDate