Troubles with nested queries - mysql

Question

I have this query which works perfectly:
SELECT *
FROM Customer
WHERE SacCode IN
(
SELECT SacCode
FROM SacCode
WHERE ResellerCorporateID = 392
ORDER BY SacCode
)
AND CustomerID IN
(
SELECT CxID
FROM CustAppointments
WHERE AppRoomID IN
(
SELECT AppRoomID
FROM ClinicRooms
WHERE ClinID IN
(
SELECT ClinID
FROM AppClinics
WHERE ClinDate >='20090101'
AND ClinDate <='20091119'
)
)
)
However, I need to see the value of ClinDate (inside the last nested query)...
How do I do it?
Thanks.

Answer 1

I'd rewrite the query using joins. Then, you can access any data from any of the joined tables.
For example, you could rewrite your query like this:
SELECT c.*, ac.ClinDate
FROM Customer c
JOIN SacCode sc ON sc.SacCode = c.SacCode
JOIN CustAppointments ca ON ca.CustomerID = c.CustomerID
JOIN ClinicRooms cr ON cr.AppRoomID = ca.AppRoomID
JOIN AppClinic ac ON ac.ClinID = cr.ClinID
WHERE ac.ClinDate >='20090101'
AND ac.ClinDate <='20091119'
AND sc.ResellerCorporateID = 392

Answer 2

Think I'd use derived table in the FROM statement rather than 3 deep nested query, will allow you to access values and will look a LOT better.

Answer 3

You'll need to copy the subselects to the FROM clause or rewrite the query using JOINs.

Answer 4

it should look something like this:
SELECT c.*, a.ClinDate
FROM Customer c
inner join CustAppointments ca
inner join ClinicRooms cr
inner join AppClinics a
where c.SacCode IN
(
SELECT SacCode
FROM SacCode
WHERE ResellerCorporateID = 392
ORDER BY SacCode
)
and c.CustomerID = ca.CxID
and ca.AppRoomID = cr.AppRoomID
and cr.ClinID = a.ClinID
and a.ClinDate >='20090101'
and a.ClinDate <='20091119'