mysql存儲過程：復制表A的某列到表B中去

mysql存儲過程：復制表A的某列到表B中去   這是一個存儲過程，用於將tableA表中avalue列的值復制到tableB表中的bvalue列（假設tableA和tableB中都有相同的列，名為id）   [sql]  create procedure copy_field()   begin       declare tid int default 0;       declare tvalue int default 0;          declare b int default 0;       declare cur cursor for select a.id, a.avalue from tableA as a join tableB as b where a.id=b.id;       DECLARE CONTINUE HANDLER FOR NOT FOUND SET b = 1;          open cur;        set b = 0;       repeat           FETCH cur INTO tid, tvalue;           update tableB set bvalue=tvalue where id=tid;           until b>0       end repeat;       close cur;   end