抱歉我的英文。 我有一个像这样的mysql表
[ --------------------------]
[ parent_id ] [ category_id ]
[ --------------------------]
网站结构如下:
0
-> 1
-> 2
-> -> 3
-> -> -> 5
-> 4
和表格看起来像
0 1
0 2
2 3
0 4
3 5
如何编写mysql while循环到输入5并获取它的父级列表,直到0:
3
2
我知道,如何在php中编写它,但我只想对数据库进行1次查询,但是当我尝试从官方手册中运行“While”示例时,它会返回很多错误。
答案 0 :(得分:0)
您可以通过程序实现此目的..
CREATE PROCEDURE `root_connect`(IN init char(1),OUT str char(15))
BEGIN
set @startChar:=(select category_id from tableName where parent_id = init);
set @endloop := "no";
set @fullchar:= @startChar;
set @newchar:= "";
if (@startChar !="-" OR @startChar =null) then
WHILE (@endloop = "no") DO
set @newchar :=(select category_id from tableName where parent_id = @startChar);
if(@newchar = '-') THEN
set @endloop := "yes";
else
set @fullchar:= concat(@fullchar,"-",@newchar);
end if;
set @startChar := @newchar;
END WHILE;
end if;
select @fullchar;
END
答案 1 :(得分:0)
每个答案都不正确,但我已经完成了。 如果有人需要,试试这个。
DELIMITER $$
DROP PROCEDURE IF EXISTS `dbName`.`getParentsTree` $$
CREATE PROCEDURE `tableName`.`getParentsTree` (IN firstChild INT, OUT tree VARCHAR(255))
BEGIN
set @newChar = (select `parent_id` from tableName where category_id = firstChild);
set @fullchar = "";
set @fullchar = @fullchar + firstChild;
WHILE (@newChar != 0) DO
SELECT CONCAT_WS(',', @fullChar, @newChar) INTO @fullChar;
set @newChar = (select `parent_id` from tableName where category_id = @newChar);
END WHILE;
SELECT @fullchar INTO tree;
END $$
DELIMITER ;
CALL dbName.getParentsTree(46, @a);
SELECT @a;
答案 2 :(得分:0)
好的把你的答案放在一起我创造了这个:
DELIMITER $$
DROP PROCEDURE IF EXISTS `dbName`.`getParentsTree` $$
CREATE PROCEDURE `dbName`.`getParentsTree` (IN firstChild INT, OUT tree VARCHAR(255))
BEGIN
set @newChar = (select `parent_id` from categories where id = firstChild);
set @newName = (select `name` from categories where id = firstChild);
set @fullchar = "" + @newName;
WHILE (@newChar != 0) DO
set @newChar = (select `parent_id` from categories where id = @newChar);
set @newName = (select `name` from categories where id = @newChar);
SELECT CONCAT_WS(' > ', @fullChar, @newName) INTO @fullChar;
END WHILE;
SELECT @fullchar INTO tree;
END $$
DELIMITER ;
访问程序
CALL dbName.getParentsTree(460, @tree);
select @tree;