Mysql游标的简明写法

-- cursor 游标
/*
declare 声明; declare 游标名 cursor for select_statement;
open 找开; open 游标名
fetch 取值; fetch 游标名 into var1,var2,var3[,...]
close 关闭; close 游标名;
*/
create procedure p12()
begin
declare row_gid int;
declare row_num int;
declare row_name varchar(20);

declare getgoods cursor for select gid,num,name from goods;

open getgoods;
fetch getgoods into row_gid,row_num,row_name;
select row_num,row_name;
close getgoods;
end;

create procedure p13()
begin
declare cnt int default 0;
declare i int default 0 ;
declare row_gid int;
declare row_num int;
declare row_name varchar(20);

declare getgoods cursor for select gid,num,name from goods;

select count(*) into cnt from goods;

open getgoods;

repeat
set i := i+1;
fetch getgoods into row_gid,row_num,row_name;
select row_num,row_name;
until i>=cnt end repeat;

close getgoods;
end;

--利用标误码来结束循环
--在mysql cursor中,可以把declare continue handler来操作1个越界标识
/*
declare continue handler for not found 语句;
*/
create procedure p14()
begin
declare row_gid int;
declare row_num int;
declare row_name varchar(20);
declare flag int default 1; --标识

declare getgoods cursor for select gid,num,name from goods;

declare continue handler for NOT FOUND set flag := 0;

open getgoods;

repeat
if flag!=0 then
fetch getgoods into row_gid,row_num,row_name;
select row_num,row_name;
end if;
until flag=0 end repeat;
close getgoods;
end;