使用mysql中的存儲過程創建更新查詢

Question

我已經在oracle中創建了存儲過程。 但是我想在mysql中運行此過程，如何在mysql中創建for循環。我對mysql中的for循環一無所知。

Create table student
  (
    Id number,
    Batch varchar2(2),
    Batch_roll_no number 
  )

Create or replace procedure assign_roll_no
Is
 V_roll_no number; 
Begin
For c1 in (select distinct batch from student order by 1)
Loop
Select nvl(Max(batch_roll_no+1),1)
Into v_roll_no
From student
 where batch = c1.batch;
  For c2 in ( select id from batch where batch_roll_no is null and batch= c1.batch
 Order by 1)
 Loop
Update student
set batch_roll_no=v_roll_no
Where id=c2.id
And batch= c1.batch;
V_roll_no:=v_roll_no + 1;
End loop;
End loop;
End;

Answer 1

點擊此鏈接。 它提供了一些簡單的示例供您懷疑。 如果您不理解鏈接的內容。 帶着疑問回到這個話題。

MySQL中的循環

就答案而言，我希望以下內容可以使Pravin清楚地了解您正在關注的場景。

DELIMITER $$ 
CREATE PROCEDURE loop_test() 
BEGIN  
WHILE c2 in (select id from batch where batch_roll_no is null and batch= c1.batch Order by 1)
DO  
Update student  
SET batch_roll_no=v_roll_no  
WHERE id=c2.id AND batch= c1.batch;  
V_roll_no:=v_roll_no + 1;  
END WHILE;  
END$$
DELIMITER ;