Question

Here is my MySQL Query that im trying to execute. it keeps failing with the error:
Unknown column ‘staff_tbl.mainrank’ in field list. how is this possible?

DROP TEMPORARY TABLE IF EXISTS `staff_tbl`;
CREATE TEMPORARY TABLE staff_tbl(childrank TEXT, mainrank TEXT);

INSERT INTO staff_tbl
SELECT permissions_inheritance.child, permissions_inheritance.parent 
FROM permissions_inheritance;

SELECT      authme.username, permissions_inheritance.child,     
permissions_inheritance.parent, staff_tbl.mainrank
FROM        authme 
INNER JOIN  permissions_inheritance ON authme.username = permissions_inheritance.child
INNER JOIN  staff_tbl alies2 ON staff_tbl.mainrank = permissions_inheritance.parent;


DROP TABLE `staff_tbl`;

I would greatly appreciate if you could help me. i have pulled every bit of my hair out. so you guys are my last hope. Im still a novice 🙂

Answer 1

In the last SELECT you have the last join wrong. You make a join with staff_tbl and give it an alias (alies2). You must use that alias in the statement that follows (alies2.mainrank = permissions_inheritance.parent instead of staff_tbl.mainrank = permissions_inheritance.parent), you didn’t.

Try writing your last SELECT like this:

SELECT      a.username, p.child, p.parent, s.mainrank
FROM        authme a
INNER JOIN  permissions_inheritance p ON a.username = p.child
INNER JOIN  staff_tbl s ON s.mainrank = p.parent;

I fixed this above. I also set an alias for each table to make the query shorter and therefore more readable.