sql的行轉列(PIVOT)與列轉行(UNPIVOT)

在做數據統計的時候，行轉列，列轉行是經常碰到的問題。case when方式太麻煩了，而且可擴展性不強，可以使用 PIVOT，UNPIVOT比較快速實現行轉列，列轉行，而且可擴展性強

一、行轉列

1、測試數據准備

CREATE  TABLE [StudentScores]
(
   [UserName]         NVARCHAR(20),        --學生姓名
   [Subject]          NVARCHAR(30),        --科目
   [Score]            FLOAT,               --成績
)

INSERT INTO [StudentScores] SELECT '張三', '語文', 80
INSERT INTO [StudentScores] SELECT '張三', '數學', 90
INSERT INTO [StudentScores] SELECT '張三', '英語', 70
INSERT INTO [StudentScores] SELECT '張三', '生物', 85
INSERT INTO [StudentScores] SELECT '李四', '語文', 80
INSERT INTO [StudentScores] SELECT '李四', '數學', 92
INSERT INTO [StudentScores] SELECT '李四', '英語', 76
INSERT INTO [StudentScores] SELECT '李四', '生物', 88
INSERT INTO [StudentScores] SELECT '碼農', '語文', 60
INSERT INTO [StudentScores] SELECT '碼農', '數學', 82
INSERT INTO [StudentScores] SELECT '碼農', '英語', 96
INSERT INTO [StudentScores] SELECT '碼農', '生物', 78

2、行轉列sql

SELECT * FROM [StudentScores] /*數據源*/
AS P
PIVOT 
(
    SUM(Score/*行轉列后 列的值*/) FOR 
    p.Subject/*需要行轉列的列*/ IN ([語文],[數學],[英語],[生物]/*列的值*/)
) AS T

執行結果：

二、列轉行

1、測試數據准備

CREATE TABLE ProgrectDetail
(
    ProgrectName         NVARCHAR(20), --工程名稱
    OverseaSupply        INT,          --海外供應商供給數量
    NativeSupply         INT,          --國內供應商供給數量
    SouthSupply          INT,          --南方供應商供給數量
    NorthSupply          INT           --北方供應商供給數量
)

INSERT INTO ProgrectDetail
SELECT 'A', 100, 200, 50, 50
UNION ALL
SELECT 'B', 200, 300, 150, 150
UNION ALL
SELECT 'C', 159, 400, 20, 320
UNION ALL

2、列轉行的sql

SELECT P.ProgrectName,P.Supplier,P.SupplyNum
FROM 
(
    SELECT ProgrectName, OverseaSupply, NativeSupply,
           SouthSupply, NorthSupply
     FROM ProgrectDetail
)T
UNPIVOT 
(
    SupplyNum FOR Supplier IN
    (OverseaSupply, NativeSupply, SouthSupply, NorthSupply )
) P

執行結果：