zoukankan      html  css  js  c++  java
  • SQL ROW_NUMBER() OVER函数的基本用法用法

    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 xlh DESC) 是先把xlh列降序,再为降序以后的没条xlh记录返回一个序号。
    示例:
    xlh           row_num
    1700              1
    1500              2
    1085              3
    710                4

    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)

    实例:

    初始化数据

    create table employee (empid int ,deptid int ,salary decimal(10,2))
    insert into employee values(1,10,5500.00)
    insert into employee values(2,10,4500.00)
    insert into employee values(3,20,1900.00)
    insert into employee values(4,20,4800.00)
    insert into employee values(5,40,6500.00)
    insert into employee values(6,40,14500.00)
    insert into employee values(7,40,44500.00)
    insert into employee values(8,50,6500.00)
    insert into employee values(9,50,7500.00)

    数据显示为

    empid       deptid      salary
    ----------- ----------- ---------------------------------------
    1           10          5500.00
    2           10          4500.00
    3           20          1900.00
    4           20          4800.00
    5           40          6500.00
    6           40          14500.00
    7           40          44500.00
    8           50          6500.00
    9           50          7500.00

    需求:根据部门分组,显示每个部门的工资等级

    预期结果:

    empid       deptid      salary                                  rank
    ----------- ----------- --------------------------------------- --------------------
    1           10          5500.00                                 1
    2           10          4500.00                                 2
    4           20          4800.00                                 1
    3           20          1900.00                                 2
    7           40          44500.00                                1
    6           40          14500.00                                2
    5           40          6500.00                                 3
    9           50          7500.00                                 1
    8           50          6500.00                                 2

    SQL脚本:

    SELECT *, Row_Number() OVER (partition by deptid ORDER BY salary desc) rank FROM employee

  • 相关阅读:
    安卓手机无法使用adb导出文件
    dex2jar 报错 com.googlecode.d2j.DexException: not support version
    夜神模拟器adb连接
    无法安装 /lib/x86_64-linux-gnu/libpng12.so.0 的新版本: 没有那个文件或目录
    mysql基础 -创建
    VScode
    阿强的TypeScript基础
    Vue由浅入深之Array变化侦测
    深入浅出Vue.js一之Object的变化侦测
    阿强工作中常用的js的数组方法汇总
  • 原文地址:https://www.cnblogs.com/itjeff/p/4191553.html
Copyright © 2011-2022 走看看