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SQL使用ROW_NUMBER() OVER函数生成序列号

MySql 2021-12-28

语法:ROW_NUMBER() OVER(PARTITION BY COLUMN ORDER BY COLUMN)
简单的说ROW_NUMBER()从1开始,为每一条分组记录返回一个数字,这里的ROW_NUMBER() OVER (ORDER BY CYLH DESC) 是先把xlh列降序,再为降序以后的每条CYLH记录返回一个序号。

示例:

SQL使用ROW_NUMBER()   OVER函数生成序列号

分析:ROW_NUMBER() OVER (PARTITION BY COL1 ORDER BY COL2) 表示根据COL1分组,在分组内部根据 COL2排序,而此函数计算的值就表示每组内部排序后的顺序编号(组内连续的唯一的)

也可这样使用:ROW_NUMBER() OVER (ORDER BY COL2)

例子:

建立测试表,并插入测试数据

 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)


执行脚本自动生成行号并按CYLH进行排序(滑动查看代码)

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


结果如下:

SQL使用ROW_NUMBER()   OVER函数生成序列号

注意:在使用over等开窗函数时,over里头的分组及排序的执行晚于“wheregroup byorder by”的执行。

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