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在工作中我们一般会遇到将横列转成纵列的需求,下面是横列转纵列的案例:
1.建表
CREATE TABLE [dbo].[AcrossChangeEndLong]( [Id] [INT] IDENTITY(1,1) NOT NULL, [Name] [NVARCHAR](50) NOT NULL, [Subject] [NVARCHAR](50) NOT NULL, [Score] [INT] NOT NULL, CONSTRAINT [PK_AcrossChangeEndLong] PRIMARY KEY CLUSTERED ( [Id] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO ALTER TABLE [dbo].[AcrossChangeEndLong] ADD CONSTRAINT [DF_AcrossChangeEndLong_Score] DEFAULT ((0)) FOR [Score] GO
2.具体SQL
SELECT Name AS ‘姓名‘, MAX(CASE [Subject] WHEN ‘语文‘ THEN Score ELSE 0 END) AS ‘语文‘ , MAX(CASE [Subject] WHEN ‘英语‘ THEN Score ELSE 0 END) AS ‘英语‘ , MAX(CASE [Subject] WHEN ‘数学‘ THEN Score ELSE 0 END) AS ‘数学‘ FROM dbo.AcrossChangeEndLong GROUP BY Name ORDER BY Name
如果到时候增加了科目,比如增加了化学,这时候为了再次修改,我们可以弄成动态的(根据列自动增加),这里使用的是动态拼接SQL,会根据科目的增加而增加列,具体SQL如下
DECLARE @sql VARCHAR(8000) SET @sql = ‘SELECT [Name],‘ SELECT @sql = @sql + ‘SUM(CASE [Subject] WHEN ‘‘‘ + [Subject] + ‘‘‘ THEN [Score] ELSE 0 END) AS ‘‘‘ + [Subject] + ‘‘‘,‘ FROM ( SELECT DISTINCT [Subject] FROM dbo.AcrossChangeEndLong ) AS a SELECT @sql = LEFT(@sql, LEN(@sql) - 1) + ‘ FROM [AcrossChangeEndLong] GROUP BY [Name]‘ PRINT ( @sql ) EXEC(@sql)
另外在SQL Server 2005之后有了一个专门的PIVOT 和 UNPIVOT 关系运算符做行列之间的转换,具体SQL如下
SELECT * FROM ( SELECT Name AS ‘姓名‘, Subject , Score FROM dbo.AcrossChangeEndLong ) p PIVOT ( MAX(Score) FOR Subject IN ( [数学], [英语], [语文] ) ) AS pvt ORDER BY pvt.姓名
使用Pivot动态拼接SQL:
DECLARE @sql_str VARCHAR(MAX) DECLARE @sql_col VARCHAR(MAX) SELECT @sql_col = ISNULL(@sql_col + ‘,‘, ‘‘) + QUOTENAME([Subject]) FROM dbo.AcrossChangeEndLong GROUP BY [Subject] SET @sql_str = ‘ SELECT * FROM ( SELECT [Name],[Subject],[Score] FROM [AcrossChangeEndLong]) p PIVOT (SUM([Score]) FOR [Subject] IN ( ‘ + @sql_col + ‘) ) AS pvt ORDER BY pvt.[Name]‘ PRINT ( @sql_str ) EXEC (@sql_str)
具体效果:
扩展:可能我们需要加一个统计行,我们可以用UNION ALL连接 上一个表的结果【可以将结果存入临时表】,再用函数SUM
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原文地址:http://www.cnblogs.com/zuqing/p/4878728.html