zoukankan      html  css  js  c++  java
  • 几条高效的分页语句

    1.使用 ROW_NUMBER() OVER 的分页查询

    SELECT *
    FROM
    (
    SELECT *, ROW_NUMBER() OVER (ORDER BY id asc) as rowNum
    FROM memberLevel
    ) AS T
    WHERE T.RowNum>=0 and T.RowNum<= 2

    相应语法:

    转自:http://www.cnblogs.com/icebutterfly/archive/2009/08/05/1539657.html

    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:
    python进阶-lambda和列表生成器
    【pandas】条件查询 分组标记
    【Python】生成html文档-使用dominate
    Python对列表内部的字典进行排序 --lambda,sort
    【python3】通过hashlib 和base64 对字符串进行加密
    【Pandas】统计某个值的出现次数
    git 创建分支,切换分支,merge操作
    如何将excel单元格中一部分数据提取到另一单元格?
    整型数的溢出解决办法
    CentOS6.9安装SonarQube7.6
  • 原文地址:https://www.cnblogs.com/cxyzl/p/2589718.html
Copyright © 2011-2022 走看看