SQL Join with Value Missing in One Column - mysql

Question

I'm trying to create a SQL query that uses one table to count the number of blade servers our company has in each chassis and groups those, while joining it with chassis information from another table.
However, one of the chassis has no blades in it, so the name does not appear in the blade inventory table. Using an INNER JOIN creates a table that doesn't contain that blade in any capacity. A LEFT JOIN achieves the same effect, but a RIGHT JOIN gives me an extra row with a null value for the chassis name.
I'm guessing this is because the non-existence of that blade name in the first table is being given precedence over the second, but not sure how to correct that. My query, as of now, looks like this:
SELECT e.EnclosureName, e.PDUName, q.Blades, r.Serial#
FROM bladeinventory.table e JOIN
(
SELECT EnclosureName,COUNT(*) Blades
FROM bladeinventory.table
GROUP BY EnclosureName
) q ON e.EnclosureName = q.EnclosureName
LEFT JOIN chassisinventory.table r
ON e.EnclosureName = r.EnclosureName
GROUP BY e.EnclosureName, e.PDUName, q.Blades, r.Serial#
Is it possible to edit this in such a way that the name of the chassis with 0 blades is actually generated by the query?

Answer 1

Just pull the name from the chassisinventory table. I'll use coalesce(), just in case you switch the order of the joins (again):
SELECT COALESCE(r.EncloseName, e.EnclosureName) as EnclosureName, e.PDUName, q.Blades, r.Serial#
FROM bladeinventory.table e JOIN
(SELECT EnclosureName,COUNT(*) Blades
FROM bladeinventory.table
GROUP BY EnclosureName
) q
ON e.EnclosureName = q.EnclosureName LEFT JOIN
chassisinventory.table r
ON e.EnclosureName = r.EnclosureName
GROUP BY COALESCE(r.EncloseName, e.EnclosureName), e.PDUName, q.Blades, r.Serial#;

Answer 2

You can also use below code where case is being used which is much simpler and effective
SELECT e.EnclosureName, r.PDUName,
case when q.Blades IS NULL then 0
else q.Blades end Blades,
e.Serial#
FROM chassisinventory.table e
LEFT OUTER JOIN bladeinventory.table r on e.EnclosureName = r.EnclosureName
LEFT OUTER JOIN (SELECT EnclosureName,COUNT(*) Blades
FROM bladeinventory.table
GROUP BY EnclosureName
) q on e.EnclosureName = q.EnclosureName