MySql ::存储过程递归 [英] MySql :: stored procedure recursive

问题描述

我该如何重写以下SP来面对MySQL中的递归限制:

how can I rewrite the following SP to face recursive limitation in MySQL:

CREATE DEFINER = `root`@`localhost` PROCEDURE `SP_DeleteParentDirectory`(pParentID INT,pIsFolder INT,pReferenceID INT)
BEGIN   
SET @@SESSION.max_sp_recursion_depth = 255;
    SET @IsFolder= NULL;
    SET @ChildID= NULL;
    SET @ReferenceID= NULL;
    IF ( pIsFolder= 2) THEN
                SELECT  FileID INTO @ChildID FROM filesinfo WHERE ParentID= pParentID LIMIT 1;
                WHILE (@ChildID IS NOT NULL) DO
                         SELECT  filesinfo.IsFolder,filesinfo.ReferenceID INTO @IsFolder,@ReferenceID FROM filesinfo WHERE filesinfo.FileID = @ChildID;
                        CALL SP_DeleteParentDirectory(@ChildID,@IsFolder,@ReferenceID);             
                        SELECT filesinfo.FileID INTO @ChildID FROM filesinfo WHERE ParentID= pParentID LIMIT 1;
                END While;
    END IF;
    DELETE FROM filesinfo Where  filesinfo.FileID= pParentID;
    IF EXISTS( SELECT  * FROM  filesrefrences WHERE filesrefrences.ReferenceID = pReferenceID AND filesrefrences.RefrenceCount>1) THEN
            UPDATE filesrefrences
            SET RefrenceCount= RefrenceCount-1 WHERE  filesrefrences.ReferenceID = pReferenceID;            
    ELSE            
            SET @ReferenceKey= NULL;
            Select filesrefrences.RefrenceKey INTO @ReferenceKey FROM filesrefrences WHERE filesrefrences.ReferenceID= pReferenceID;
            IF NOT EXISTS(SELECT * FROM deletefilesreferences WHERE deletefilesreferences.FileReference= @ReferenceKey) THEN
            INSERT INTO deletefilesreferences (deletefilesreferences.FileReference)VALUES(@ReferenceKey);
            END IF;
            DELETE FROM filesrefrences where filesrefrences.ReferenceID = pReferenceID;         
    END IF;
    -- CALL SP_DeleteFileInfo(pParentID,pReferenceID);      
    -- SELECT * FROM deletefilesreferences;
    -- CALL SP_GetDeletedReferences();
END;

不使用此sts:

" SET @@ SESSION.max_sp_recursion_depth = 255; " 我的意思是，它可以与层次结构数据进行交互而无需递归.

"SET @@SESSION.max_sp_recursion_depth = 255;" I mean that can interact with hierarchy data without recursion.

推荐答案

如果设置max_sp_recursion_depth，则MySQL在过程中最多允许255个递归.

Mysql allows up to 255 recursion in a PROCEDURE if you set max_sp_recursion_depth.

这很冒险，因为将来某个时候所需的递归深度可能会超过255.

Its risky because there is a chance that the needed recursion depth may exceed 255 sometime in future.

因此，最好使用一个过程替换函数，对return_result使用 INOUT 变量.

So Its better you replace your function with a procedure, using an INOUT variable for the return_result.

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