【sas sql proc】case end

在sql中增加case可以增加数据处理的灵活性，注意结尾的end

proc sql outobs=10;
    title 'this is an example of sql and case';
    select wangnei,date,
            case
            when 200901<=date<=200903 then 'first'
            when 200904<=date<=200906 then 'second'
            else 'else'
            end as season
    from mysas.mmsone
    where date<=200912;
quit;

 ---------sas 9.3 sql procedure user's guide page 35 or (49/418)

 在where字句后还可以加上许多operator

any all between-and contains exists in isnull is missing like =* 

in

proc contents data=mysas.ifthen; 
run;
proc print data=mysas.ifthen (firstobs=1 obs=10);
run;
proc sql outobs=10;
    title 'this is a instance of in';
    select * from mysas.ifthen
    where date in(200901,200902)
    order by shen descending;
quit;

between and

proc sql outobs=10;
    title 'this is a try of between and';
    select * from mysas.ifthen
    where date between 200905 and 201001
    order by shen dscending;
quit;

like

proc sql outobs=50;
    select * from &dataset
    where  subporduct_code like 'z%' or subporduct_code like 'XX____';
quit;

 在where筛选条件中对于排序文本也可以用大于小于的逻辑来判断：eqt gtt ltt get let net.