Group By column throwing off query - sql

Question

I have a query that checks a database to see if a customer has visited multiple times a day. If they have it counts the number of visits, and then tells me what times they visited. The problem is it throws "Tickets.lcustomerid" into the group by clause, causing me to miss 5 records (Customers without barcodes). How can I change the below query to remove "tickets.lcustomerid" from the group by clause... If I remove it I get an error telling me "Tickets.lCustomerID" is not a valid select because it's not part of an aggregate or groupby clause.
The Query that works:
SELECT Customers.sBarcode, CAST(FLOOR(CAST(Tickets.dtCreated AS FLOAT)) AS DATETIME) AS dtCreatedDate, COUNT(Customers.sBarcode) AS [Number of Scans],
MAX(Customers.sLastName) AS LastName
FROM Tickets INNER JOIN
Customers ON Tickets.lCustomerID = Customers.lCustomerID
WHERE (Tickets.dtCreated BETWEEN #startdate AND #enddate) AND (Tickets.dblTotal <= 0)
GROUP BY Customers.sBarcode, CAST(FLOOR(CAST(Tickets.dtCreated AS FLOAT)) AS DATETIME)
HAVING (COUNT(*) > 1)
ORDER BY dtCreatedDate
The Output is:
sBarcode dtcreated Date Number of Scans slastname
1234 1/4/2013 12:00:00 AM 2 Jimbo
1/5/2013 12:00:00 AM 3 Jimbo2
1578 1/6/2013 12:00:00 AM 3 Jimbo3
My current Query with the subquery
SELECT customers.sbarcode,
Max(customers.slastname) AS LastName,
Cast(Floor(Cast(tickets.dtcreated AS FLOAT)) AS DATETIME) AS
dtCreatedDate,
Count(customers.sbarcode) AS
[Number of Scans],
Stuff ((SELECT ', '
+ RIGHT(CONVERT(VARCHAR, dtcreated, 100), 7) AS [text()]
FROM tickets AS sub
WHERE ( lcustomerid = tickets.lcustomerid )
AND ( dtcreated BETWEEN Cast(Floor(Cast(tickets.dtcreated
AS
FLOAT)) AS
DATETIME
)
AND
Cast(Floor(Cast(tickets.dtcreated
AS FLOAT
)) AS
DATETIME
)
+ '23:59:59' )
AND ( dbltotal <= '0' )
FOR xml path('')), 1, 1, '') AS [Times Scanned]
FROM tickets
INNER JOIN customers
ON tickets.lcustomerid = customers.lcustomerid
WHERE ( tickets.dtcreated BETWEEN #startdate AND #enddate )
AND ( tickets.dbltotal <= 0 )
GROUP BY customers.sbarcode,
Cast(Floor(Cast(tickets.dtcreated AS FLOAT)) AS DATETIME),
tickets.lcustomerid
HAVING ( Count(*) > 1 )
ORDER BY dtcreateddate
The Current output (notice the record without a barcode is missing) is:
sBarcode dtcreated Date Number of Scans slastname Times Scanned
1234 1/4/2013 12:00:00 AM 2 Jimbo 12:00PM, 1:00PM
1578 1/6/2013 12:00:00 AM 3 Jimbo3 03:05PM, 1:34PM

Answer 1

UPDATE: Based on our "chat" it seems that customerid is not the unique field but barcode is, even though customer id is the primary key.
Therefore, in order to not GROUP BY customer id in the subquery you need to join to a second customers table in there in order to actually join on barcode.
Try this:
SELECT customers.sbarcode,
Max(customers.slastname) AS LastName,
Cast(Floor(Cast(tickets.dtcreated AS FLOAT)) AS DATETIME) AS
dtCreatedDate,
Count(customers.sbarcode) AS
[Number of Scans],
Stuff ((SELECT ', '
+ RIGHT(CONVERT(VARCHAR, dtcreated, 100), 7) AS [text()]
FROM tickets AS subticket
inner join
customers as subcustomers
on
subcustomers.lcustomerid = subticket.lcustomerid
WHERE ( subcustomers.sbarcode = customers.sbarcode )
AND ( subticket.dtcreated BETWEEN Cast(Floor(Cast(tickets.dtcreated
AS
FLOAT)) AS
DATETIME
)
AND
Cast(Floor(Cast(tickets.dtcreated
AS FLOAT
)) AS
DATETIME
)
+ '23:59:59' )
AND ( dbltotal <= '0' )
FOR xml path('')), 1, 1, '') AS [Times Scanned]
FROM tickets
INNER JOIN customers
ON tickets.lcustomerid = customers.lcustomerid
WHERE ( tickets.dtcreated BETWEEN #startdate AND #enddate )
AND ( tickets.dbltotal <= 0 )
GROUP BY customers.sbarcode,
Cast(Floor(Cast(tickets.dtcreated AS FLOAT)) AS DATETIME)
HAVING ( Count(*) > 1 )
ORDER BY dtcreateddate

Answer 2

I can't directly solve your problem because I don't understand your data model or what you are trying to accomplish with this query. However, I can give you some advice on how to solve the problem yourself.
First do you understand exactly what you are trying to accomplish and how the tables fit together? If so move on to the next step, if not, get this knowledge first, you cannot do complex queries without this understanding.
Next break up what you are trying to accomplish in little steps and make sure you have each covered before moving to the rest. So in your case you seem to be missing some customers. Start with a new query (I'm pretty sure this one has more than one problem). So start with the join and the where clauses.
I suspect you may need to start with customers and left join to tickets (which would move the where conditions to the left joins as they are on tickets). This will get you all the customers whether they have tickets or not. If that isn't what you want, then work with the jon and the where clasues (and use select * while you are trying to figure things out) until you are returning the exact set of customer records you need. The reason why you use select * at this stage is to see what in the data may be causeing the problem you are having. That may tell you how to fix.
Usually I start with a the join and then add in the where clasues one at a time until I know I am getting the right inital set of records. If you have multiple joins, do them one at time to know when you suddenly start have more or less records than you would expect.
Then go into the more complex parts. Add each in one at a time and check the results. If you suddenly go from 10 records to 5 or 15, then you have probably hit a problem. When you work one step at a time and run into a problem, you know exactly what caused the problem making it much easier to find and fix.
Group BY is important to understand thoroughly. You must have every non-aggregated field in the group by or it will not work. Think of this as law like the law of gravity. It is not something you can change. However it can be worked around through the use of derived tables or CTEs. Please read up on those a bit if you don't know what they are, they are very useful techniques when you get into complex stuff and you shoud understand them thoroughly. I suspect you will need to use the derived table approach here to group on only the things you need and then join that derived table to the rest of teh query to get the ontehr fields. I'll show a simple example:
select
t1.table1id
, t1.field1
, t1.field2
, a.field3
, a.MostRecentDate
From table1 t1
JOIN
(select t1.table1id, t2.field3, max (datefield) as MostRecentDate
from table1 t1
JOin Table2 t2 on t1.table1id = t2.table1id
Where t2.field4 = 'test'
group by t1.table1id,t2.field3) a
ON a.table1id = t1.table1id
Hope this approach helps you solve this problem.