使用IF...ELSE语句判断日期是否为周日

小朋友作业操碎心，看代码： 

use test;
delimiter $$     
create procedure pre12()		
BEGIN 
declare issunday int;  
declare datastrtest varchar(255); 
declare i int;		
set i=1;
while i<3 do	
SELECT datastrinner, days into datastrtest,issunday  FROM (SELECT  datastr as datastrinner ,DAYOFWEEK(datastr) AS days  FROM test.test_week where id=i) tmp;
if issunday = 1 then 
    select datastrtest,issunday,"是" as "是否为周日";  
else 
    select datastrtest,issunday,"不是" as "是否为周日";  
end if;  
set i=i+1;	
end while;
END 
$$		
 
call pre12();