Question

Org_table:

OrgName    Id    ParentID
 Org1      20    Null
 Org2      21    20
 Org3      22    21
 Org4      23    21
 Org5      24    22
 Org6      25    Null

In the table above Org1 is the super organisation and Org2 is the child of Org1. And Sub Org of Org2 is Org3 and Org4. and Org 5 is sub Org of Org3

I want to display all the details of these Org under the parent Org1 in my data grid. Here I know only the Org1 ID
so mysql query is like

Select OrgName from Org_table where ID= 20 and ParentID is 20;

But this query returns only Org1 and Org2, I have to return Org3, Org4 and Org5 also because it is under Org1. How can I do it. should I use some kind of loop if so how to do it. I am using c# do this is in my asp.net website.

During runtime I wont know which org is child of which ORg. SO I have to find the If the parent id is under the main Org

I want to do recursive query

Answer 1

I don’t have mysql on hand, but this should do what you need

CREATE TEMPORARY TABLE TempTable (OrgName VARCHAR(10), Id INT, ParentID INT); 

INSERT INTO TempTable SELECT OrgName, Id, ParentID FROM org_table;

WHILE EXISTS (SELECT TOP 1 1 FROM TempTable WHERE EXISTS(SELECT TOP 1 1 FROM TempTable TempTableParent WHERE TempTableParent.ID = TempTable.ParentID AND TempTableParent.ParentID IS NOT NULL) ) DO

UPDATE TempTable SET ParentID = TempTableParent .parentID
FROM TempTable
INNER JOIN TempTable TempTableParent ON TempTableParent.id = TempTable.ParentID
WHERE TempTable.ParentID IS NOT NULL AND TempTableParent.ParentID IS NOT NULL

END WHILE;

SELECT * FROM TempTable

Not sure if the syntax on the update statement is entirely correct for mysql.. might need to be tweeked a little.