SQL分析函数学习
一、分析函数语法：
function_name(<argument>,<argument>...) over(<partition_Clause><order by_Clause><windowing_Clause>);
function_name()：函数名称
argument：参数
over( )：开窗函数
partition_Clause：分区子句，数据记录集分组，group by...
order by_Clause：排序子句，数据记录集排序，order by...
windowing_Clause：开窗子句，定义分析函数在操作行的集合，三种开窗方式：rows、range、Specifying
注：使用开窗子句时一定要有排序子句！！！
二、分析函数如下：
1、count() over() ：统计分区中各组的行数，partition by 可选，order by 可选
1、select name, sex, age, count(*) over() from emp; --总计数 2、select name, sex, age, count(*) over(order by age) from emp; --递加计数 3、select name, sex, age, count(*) over(partition by sex) from emp; --分组计数 4、select name, sex, age, count(*) over(partition by sex order by age) from emp;--分组递加计数
2、sum() over() ：统计分区中记录的总和，partition by 可选，order by 可选
1、select name, sex, age, sum(salary) over() from emp; --总累计求和 2、select name, sex, age, sum(salary) over(order by age) from emp; --递加累计求和 3、select name, sex, age, sum(salary) over(partition by sex) from emp; --分组累计求和 4、select name, sex, age, sum(salary) over(partition by sex order by age) from emp; --分组递加累计求和
3、avg() over() ：统计分区中记录的平均值，partition by 可选，order by 可选
1、select name, sex, age, avg(salary) over() from emp; --总平均值 2、select name, sex, age, avg(salary) over(order by age) from emp; --递加求平均值 3、select name, sex, age, avg(salary) over(partition by sex) from emp; --分组求平均值 4、select name, sex, age, avg(salary) over(partition by sex order by age) from emp; --分组递加求平均值
4、min() over() ：统计分区中记录的最小值，partition by 可选，order by 可选
max() over() ：统计分区中记录的最大值，partition by 可选，order by 可选
1、select name, sex, age, salary, min(salary) over() from emp; --求总最小值 2、select name, sex, age, salary, min(salary) over(order by age) from emp; --递加求最小值 3、select name, sex, age, salary, min(salary) over(partition by sex) from emp; --分组求最小值 4、select name, sex, age, salary, min(salary) over(partition by sex order by age) from emp; --分组递加求最小值 5、select name, sex, age, salary, max(salary) over() from emp; --求总最大值 6、select name, sex, age, salary, max(salary) over(order by age) from emp; --递加求最大值 7、select name, sex, age, salary, max(salary) over(partition by sex) from emp; --分组求最大值 8、select name, sex, age, salary, max(salary) over(partition by sex order by age) from emp; --分组递加求最大值
5、rank() over() ：跳跃排序，partition by 可选，order by 必选
1、select name, age, rank() over(partition by job order by age) from emp; 2、select name, age, rank() over(order by age) from emp;
6、dense_rank() ：连续排序，partition by 可选，order by 必选
1、select name, age, dense_rank() over(partition by job order by age) from emp; 2、select name, age, dense_rank() over(order by age) from emp;
7、row_number() over() ：排序，无重复值，partition by 可选，order by 必选
1、select name, age, row_number() over(partition by job order by age) from emp; 2、select name, age, row_number() over(order by age) from emp;
8、ntile(n) over() ：partition by 可选，order by 必选
n表示将分区内记录平均分成n份，多出的按照顺序依次分给前面的组
select name, salary, ntile(3) over(order by salary desc) from emp; select name, salary, ntile(3) over(partition by job order by salary desc) from emp;
9、first_value() over() ：取出分区中第一条记录的字段值，partition by 可选，order by 可选
last_value() over() ：取出分区中最后一条记录的字段值，partition by 可选，order by 可选
1、select name, first_value(salary) over() from emp; 2、select name, first_value(salary) over(order by salary desc) from emp; 3、select name, first_value(salary) over(partition by job) from emp; 4、select name, first_value(salary) over(partition by job order by salary desc) from emp; 5、select name, last_value(ename) over() from emp; 6、select name, last_value(ename) over(order by salary desc) from emp; 7、select name, last_value(ename) over(partition by job) from emp; 8、select name, last_value(ename) over(partition by job order by salary desc) from emp;
10、first ：从DENSE_RANK返回的集合中取出排在最前面的一个值的行
last ：从DENSE_RANK返回的集合中取出排在最后面的一个值的行
select job, max(salary) keep(dense_rank first order by salary desc), max(salary) keep(dense_rank last order by salary desc) from emp group by job;
11、lag() over() ：取出前n行数据，partition by 可选，order by 必选
lead() over() ：取出后n行数据，partition by 可选，order by 必选
1、select name, age, lag(age,1,0) over(order by salary), lead(age,1,0) over(order by salary) from emp; 2、select name, age, lag(age,1) over(partition by sex order by salary), lead(age,1) over(partition by sex order by salary) from emp;
12、ratio_to_report(a) over(partition by b) ：求按照b分组后a的值在所属分组中总值的占比,a的值必须为数值或数值型字段
partition by 可选，order by 不可选
1、select name, job, salary, ratio_to_report(1) over() from emp; --给每一行赋值1，求当前行在总值的占比，总是0.1 2、select name, job, salary, ratio_to_report(salary) over() from emp; --当前行的值在所有数据中的占比 3、select name, job, salary, ratio_to_report(1) over(partition by job) from emp; --给每一行赋值1，求当前行在分组后的组内总值的占比 4、select name, job, salary, ratio_to_report(salary) over(partition by job) from emp; --当前行的值在分组后组内总值占比
13、percent_rank() over() ：partition by 可选，order by 必选
所在组排名序号-1除以该组所有的行数-1，排名跳跃排序
1、select name, job, salary, percent_rank() over(order by salary) from emp; 2、select name, job, salary, percent_rank() over(partition by job order by salary) from emp;
14、cume_dist() over() ：partition by 可选，order by必选
所在组排名序号除以该组所有的行数，注意对于重复行，计算时取重复行中的最后一行的位置
1、select name, job, salary, cume_dist() over(order by salary) from emp; 2、select name, job, salary, cume_dist() over(partition by job order by salary) from emp;
15、precentile_cont( x ) within group(order by ...) over() ：over()中partition by可选，order by 不可选
x为输入的百分比，是0-1之间的一个小数，返回该百分比位置的数据，若没有则返回以下计算值（r）：
a=1+( x *(N-1) ) x为输入的百分比，N为分区内的记录的行数
b=ceil ( a ) 向上取整
c = floor( a ) 向下取整
r=a * 百分比位置上一条数据 + b * 百分比位置下一条数据
1、select name, job, salary, percentile_cont(0.5) within group(order by salary) over() from emp; 2、select name, job, salary, percentile_cont(0.5) within group(order by salary) over(partition by job) from emp;
16、precentile_disc( x ) within group(order by ...) over() ：over()中partition by可选，order by 不可选
x为输入的百分比，是0-1之间的一个小数，返回百分比位置对应位置上的数据值，若没有对应数据值，就取大于该分布值的下一个值
1、select name, job, salary, percentile_disc(0.5) within group(order by salary) over()from emp; 2、select name, job, salary, percentile_disc(0.5) within group(order by salary) over(partition by job) from emp;
17、stddev() over()：计算样本标准差，只有一行数据时返回0，partition by 可选，order by 可选
stddev_samp() over()：计算样本标准差，只有一行数据时返回null，partition by 可选，order by 可选
stddev_pop() over()：计算总体标准差，partition by 可选，order by 可选
1、select stddev(stu_age) over() from student; --计算所有记录的样本标准差 2、select stddev(stu_age) over(order by stu_age) from student; --计算递加的样本标准差 3、select stddev(stu_age) over(partition by stu_major) from student; --计算分组的样本标准差 4、select stddev(stu_age) over(partition by stu_major order by stu_age) from student; --计算分组递加的样本标准差 5、select stddev_samp(stu_age) over() from student; --计算所有记录的样本标准差 6、select stddev_samp(stu_age) over(order by stu_age) from student; --计算递加的样本标准差 7、select stddev_samp(stu_age) over(partition by stu_major) from student; --计算分组的样本标准差 8、select stddev_samp(stu_age) over(partition by stu_major order by stu_age) from student; --计算分组递加的样本标准差 9、select stddev_pop(stu_age) over() from student; --计算所有记录的总体标准差 10、select stddev_pop(stu_age) over(order by stu_age) from student; --计算递加的总体标准差 11、select stddev_pop(stu_age) over(partition by stu_major) from student; --计算分组的总体标准差 12、select stddev_pop(stu_age) over(partition by stu_major order by stu_age) from student;--计算分组递加的总体标准差
18、variance() over()：计算样本方差，只有一行数据时返回0，partition by 可选，order by 可选
var_samp() over()：计算样本方差，只有一行数据时返回null，partition by 可选，order by 可选
var_pop() over()：计算总体方差，partition by 可选，order by 可选
1、select variance(stu_age) over() from student; --计算所有记录的样本方差 2、select variance(stu_age) over(order by stu_age) from student; --计算递加的样本方差 3、select variance(stu_age) over(partition by stu_major) from student; --计算分组的样本方差 4、select variance(stu_age) over(partition by stu_major order by stu_age) from student; --计算分组递加的样本方差 5、select var_samp(stu_age) over() from student; --计算所有记录的样本方差 6、select var_samp(stu_age) over(order by stu_age) from student; --计算递加的样本方差 7、select var_samp(stu_age) over(partition by stu_major) from student; --计算分组的样本方差 8、select var_samp(stu_age) over(partition by stu_major order by stu_age) from student; --计算分组递加的样本方差 9、select var_pop(stu_age) over() from student; --记录所有就的总体方差 10、select var_pop(stu_age) over(order by stu_age) from student; --计算递加的总体方差 11、select var_pop(stu_age) over(partition by stu_major) from student; --计算分组的总体方差 12、select var_pop(stu_age) over(partition by stu_major order by stu_age) from student;--计算分组递加的样本方差
stddev()=sqrt( variance() ) sqrt()--求开方
stddev_samp()=sqrt( var_samp() )
stddec_pop=sqrt( var_pop() )
19、covar_samp over()：返回一对表达式的样本协方差，partition by 可选，order by 可选
covar_pop over()： 返回一堆表达式的总体协方差，partition by 可选，order by 可选
1、select covar_samp(stu_age,line) over() from student; --计算所有记录的样本协方差 2、select covar_samp(stu_age,line) over(order by stu_age) from student; --计算递加的样本协方差 3、select covar_samp(stu_age,line) over(partition by stu_major) from student; --计算分组的样本协方差 4、select covar_samp(stu_age,line) over(partition by stu_major order by stu_age) from student; --计算分组递加的样本协方差 5、select covar_pop(stu_age,line) over() from student; --计算所有记录的总体协方差 6、select covar_pop(stu_age,line) over(order by stu_age) from student; --计算递加的总体协方差 7、select covar_pop(stu_age,line) over(partition by stu_major) from student; --计算分组的总体协方差 8、select covar_pop(stu_age,line) over(partition by stu_major order by stu_age) from student; --计算分组递加的总体协方差
20、corr() over() ：返回一对表达式的相关系数，partition by 可选，order by 可选
1、select corr(stu_age,line) over() from student; --计算所有记录的相关系数 2、select corr(stu_age,line) over(order by stu_age) from student; --计算递加的相关系数 3、select corr(stu_age,line) over(partition by stu_major) from student; --计算分组的相关系数 4、select corr(stu_age,line) over(partition by stu_major order by stu_age) from student; --计算分组递加的相关系数
21、REGR_ (Linear Regression) Functions：这些线性回归函数适合最小二乘法回归线，有9个不同的回归函数可使用
