SQL query with joins help needed - sql

Question

I have four tables.
DocumentList:
DocumentID int
DocumentDescription varchar(100)
DocumentName varchar(100)
DocumentTypeCode int
Archive ud_DefaultBitFalse:bit
DocumentStepLevel:
DocumentStepID int
DocumentID int
StepLevelCode int
DocumentAttachment:
DocumentAttachmentGenID int
DocumentStepID int
AttachmentGenID int
FacilityGenID int
Submitted ud_DefaultBitFalse:bit
Attachment:
AttachmentGenId int
FileName varchar(255)
FileDescription varchar(255)
UploadDate ud_DefaultDate:datetime
DocumentData varbinary(MAX)
MimeType varchar(30)
Archive ud_DefaultBitFalse:bit
UpdateBy int
UpdateDate ud_DefaultDate:datetime
Documentlist table contains a list of documents.
DocumentStepLevel is a table that associate documents in DocumentList with a step level. We have six steps right now and each step have some documents associated with it.
DocumentAttachment table is junction/relationship table that create relationship between DocumentStepLevel and Attachment table.
Attachment table has the actual files data uploaded to the system
Question:
I need to write a query that will fetch the following columns.
DocumentList.[DocumentDescription]
DocumentList.[DocumentName]
DocumentStepLevel.[DocumentStepID]
DocumentStepLevel.[StepLevelCode]
DocumentAttachment.[DocumentAttachmentGenID]
DocumentAttachment.[FacilityGenID]
DocumentAttachment.[Submitted]
Attachment.[FileName]
Attachment.[FileDescription]
Attachment.[UploadDate]
Query should return data from DocumentList table for specific step level. When DocumentAttachment.[Submitted] column is set to true it should also return the data from DocumentAttachment and Attachment tables as well. Otherwise those columns will return nothing.
I tried using left outer join but problem happen when I add Submitted column to query. When I add that column to query it stop returning any data until that flag is set to true.

Answer 1

SELECT *
FROM documentStepLevel dsl
JOIN documentList dl
ON dl.documentId = dsl.documentId
LEFT JOIN
documentAttachment da
ON da.documentStepID = dsl.documentStepId
AND submitted = 1
LEFT JOIN
attachment a
ON a.attachmentGenId = da.attachmentGenId
WHERE dsl.stepLevelCode = #stepLevelCode

Answer 2

Is it DocumentAttachment you're left outer joining?
Difficult to say for sure without seeing your current query, but I'm guessing you've outer joined to DocumentAttachment and then have something like "where documentattachment.submitted = 1"?
In this case I believe it won't return anything as for rows where documentattachment doesn't exist, submitted is effectively null. So you might need to change your where statement to "where (documentattachment.submitted = 1 or documentattachment.submitted is null)"
This also assumes that when DocumentAttachment is populated, submitted by default has a 0 value rather than a null value (otherwise you'll need a different method of ascertaining the absence of a DocumentAttachment)