mysql - 试图返回父记录的所有子记录列

Question

我正在寻找一种解决方案，通过它我可以获得父记录的所有子记录。 <强> I found a solution that meet my needs as shown here

唯一的问题是上述解决方案是连接 ID。

当前结果集

ID 列以逗号分隔，值为 2,3,4

预期输出

ID    Name    ParentID
1      1st       null
2      2nd       1
3      3rd       1
4      4th       2

我试过下面的代码。

SELECT @pv:=
(SELECT * FROM tblreport WHERE ParentID IN (@pv)) AS lv FROM tblreport
JOIN
(SELECT @pv:=2)tmp
WHERE ParentID IN (@pv)

并收到一条错误消息:Operand should contain 1 column(s)

My sample SQL Fiddle

Answer 1

Now, they are coming comma separated. But, I am expecting to return all columns of a particular row.

您可以使用 CSV id 结果，例如:

SELECT *
FROM tblreport
WHERE FIND_IN_SET(ID,(SELECT GROUP_CONCAT(lv SEPARATOR ',') FROM (
                     SELECT @pv:=(SELECT GROUP_CONCAT(ID SEPARATOR ',') 
                     FROM tblreport WHERE ParentID IN (@pv)) AS lv FROM tblreport
                     JOIN (SELECT @pv:=1)tmp
                       WHERE ParentID IN (@pv)) a));

DBFiddle Demo

输出:

ID  Name    ParentID
2   2nd     1
3   3rd     1
4   4th     2

编辑:

如果您还需要原始行，您可以使用UNION ALL:

SET @var = 1;

SELECT *
FROM tblreport
WHERE FIND_IN_SET(ID,(SELECT GROUP_CONCAT(lv SEPARATOR ',') FROM (
                     SELECT @pv:=(SELECT GROUP_CONCAT(ID SEPARATOR ',') 
                     FROM tblreport WHERE ParentID IN (@pv)) AS lv FROM tblreport
                     JOIN (SELECT @pv:=@var)tmp
                       WHERE ParentID IN (@pv)) a))

UNION ALL
SELECT *
FROM tblReport
WHERE ID = @var
ORDER BY ID;

DBFiddle Demo2