SQL使用ROW_NUMBER() OVER函數自動生成序列號

語法：ROW_NUMBER() OVER(PARTITION BY COLUMN ORDER BY COLUMN)

簡單的說ROW_NUMBER()從1開始，為每一條分組記錄返回一個數字，這里的ROW_NUMBER() OVER (ORDER BY CYLH DESC) 是先把xlh列降序，再為降序以后的每條CYLH記錄返回一個序號。 

示例：  CYLH        ROW_MUM

           1900              1 

           1600              2 

           1185              3 

           780                4

分析：ROW_NUMBER() OVER (PARTITION BY COL1 ORDER BY COL2) 表示根據COL1分組，在分組內部根據 COL2排序，而此函數計算的值就表示每組內部排序后的順序編號（組內連續的唯一的)

也可這樣使用：ROW_NUMBER() OVER (ORDER BY COL2)

例子：

建立測試表，並插入測試數據

 CREATE TABLE TEST_ROW_NUMBER_01(
       CMZH varchar(10) not null,
       CYLH varchar(10) null,
       MJE money null,
);

INSERT INTO TEST_ROW_NUMBER_01(CMZH,CYLH,MJE) VALUES (2106000011,20281997,10.50)
INSERT INTO TEST_ROW_NUMBER_01(CMZH,CYLH,MJE) VALUES(2106000010,20281996,10.50)
INSERT INTO TEST_ROW_NUMBER_01(CMZH,CYLH,MJE) VALUES(2106000008,20281995,0.00)
INSERT INTO TEST_ROW_NUMBER_01(CMZH,CYLH,MJE) VALUES(2106000006,20281994,9.50)
INSERT INTO TEST_ROW_NUMBER_01(CMZH,CYLH,MJE) VALUES(2106000004,20281993,5.50)
INSERT INTO TEST_ROW_NUMBER_01(CMZH,CYLH,MJE) VALUES(2106000001,20281992,10.50)
INSERT INTO TEST_ROW_NUMBER_01(CMZH,CYLH,MJE) VALUES(2106000002,20281992,10.50)
INSERT INTO TEST_ROW_NUMBER_01(CMZH,CYLH,MJE) VALUES(2106000007,20217280,0.00)
INSERT INTO TEST_ROW_NUMBER_01(CMZH,CYLH,MJE) VALUES(2106000009,20172458,5.50)
INSERT INTO TEST_ROW_NUMBER_01(CMZH,CYLH,MJE) VALUES(2106000005,20121813,0.00)

執行腳本自動生成行號並按CYLH進行排序（滑動查看代碼）

SELECT ROW_NUMBER()OVER(ORDER BY CYLH DESC) AS ROWNUM,* FROM TEST_ROW_NUMBER_01

結果如下：

 

 注意：在使用over等開窗函數時，over里頭的分組及排序的執行晚於“where，group by，order by”的執行。