mysql 存储过程迭代获取数据

项目中有需要根据ParentId查询ChildId,由于mysql本身不能提供迭代的函数。因此使用存储过程迭代查询。记录在此，下次可以直接复制使用。

DECLARE _effectrow int;
  DECLARE _max int;
  set  _max=0;
  SET _effectrow=1;
  #获取所有商品种类的顶级ID
  DROP TEMPORARY TABLE IF EXISTS temp_catagory;
  CREATE TEMPORARY TABLE temp_catagory(catagoryid bigint,level int);
  DROP TEMPORARY TABLE IF EXISTS temp_mid_catagory;
  CREATE TEMPORARY TABLE temp_mid_catagory(catagoryid bigint);
  
  INSERT temp_catagory(catagoryid,level) SELECT id,0 FROM catalogs WHERE CompanyId=_companyid AND ParentId=0;
  outer_label:   #设置一个标记
    WHILE _effectrow>0 DO 
      set _max=_max+1;
      IF _max>10 THEN 
        LEAVE outer_label ;
      END IF;
      #获取所有商品种类的子商品种类
      INSERT temp_mid_catagory(catagoryid) 
        SELECT id FROM catalogs a WHERE  CompanyId=_companyid AND 
        EXISTS(SELECT 1 FROM temp_catagory b WHERE a.ParentId=b.catagoryid AND LEVEL=(_max-1));
      SET _effectrow=ROW_COUNT();

      IF _effectrow>0 THEN
         INSERT temp_catagory(catagoryid,level) SELECT catagoryid,_max  FROM temp_mid_catagory;
         DELETE FROM temp_mid_catagory;
      END IF;
    END WHILE;
       # SELECT * FROM temp_catagory;