sas中的sql(1) 基本语法

 proc sql;    
     select membertype, sum(milestraveled) as TotalMiles   
                 from sasuser.frequentflyers        
        group by membertype;      /*group by后面接select中所有没有经过summary函数的变量才有用，否则不能得出分组效果*/
quit;

proc sql;      
select jobcode,     
       avg(salary) as AvgSalary     format=dollar11.2        
        from sasuser.payrollmaster     
        group by jobcode        
        having avg(salary) > (select avg(salary) from sasuser.payrollmaster);
quit; 

/*先执行子查询中的语句，计算出出所有salary的平均值，然后在having子句中，用每个group的avg工资与子查询得出的总的avg工资进行比较，筛选出想要的结果*/

proc sql;
    create table class as 
    select /*select和from中间全部是要获取的变量,分为两种，一种是数据集本身已有的，另一种是由其衍生的变量*/ 
    name,
    case when sex eq ‘女‘ then ‘1‘
         when sex eq ‘男‘ then ‘2‘
         else ‘3‘
    end
    as sex_tran label="性别转换", /*as做为关键字，形成一个变量，label是sas中的关键字*/
    sum(weight-20) as new1 format=16.2,
    mean(height-20) as new2 format=16.2,/*一般来说sum mean后面一定会出现group by 因为是要根据组别进行汇总*/
    (calculated new1-calculated new2) as new /*calculated为关键字，表示new1是衍生的变量，如果需要对其进行操作的话要加上calculated*/
    from sashelp.class(where=(height between 50 and 70)) /*sas中between and是闭区间*/
    group by name,calculated sex_tran/*除开group by后面的字段外，select中其他字段必须是数值型，不然无法进行group*/
    /*group系统默认按照升序排列后面的字段*/
    order by calculated sex_tran desc/*对想要进行降序的字段可额外进行order by*/
;
quit;

/*having语句一般跟在group by后面，如果单独来用，其作用和where差不多*/
proc sql;
    create table have1 as
    select 
        id,
        max(txn_seq) as max_txn,
        sum(amount) as sum_amount
    from temp.having1
    group by id
    having calculated sum_amount ge 70
;    
quit;

/*目标是去除每一组的最后一条观测，但是使用having在分组相关变量有重复的情况下不保险，所以能用data步处理尽量用data步*/
proc sql;
    create table have2 as
    select 
        id,
        txn_seq,
        amount
    from temp.having2
    group by id
    having txn_seq eq max(txn_seq)
;    
quit;