Left outer join multiple selects - sql

Question

I have the following sql statement, that does exactly what it should:
select C.Company_RecID, C.Contact_RecID, C.First_Name, C.Last_Name,
C.Title, C.Inactive_Flag, e.Description
FROM dbo.Contact AS C
LEFT OUTER JOIN dbo.Contact_Communication AS e ON C.Contact_RecID = e.Contact_RecID
AND e.Communication_Type_RecID = 1 AND e.Default_Flag = 1
However, in dbo.contact_communication, the description field means different things depending upon the communication_type_recID. If it's 1, description is an email address. If it's 4, it's a cell phone number, if it's 2, it's a direct number, and if it's 14, it's a personal cell phone number.
I'd like to change the query to return three additional columns. Column 8 would be the value of description if there is a record for this contact with a recid of 4, column 9 the value of description if there is a record for this contact with a recid of 2, and column 10 if there is a value of 14.

Answer 1

Something like this should be pretty close as I understand what you are looking for.
select C.Company_RecID
, C.Contact_RecID
, C.First_Name
, C.Last_Name
, C.Title
, C.Inactive_Flag
, e.Description
, EmailAddress = MAX(case when communication_type_recID = 1 then e.Description end)
, CellPhone = MAX(case when communication_type_recID = 4 then e.Description end)
, DirectNumber = MAX(case when communication_type_recID = 2 then e.Description end)
, PersonalCellPhone = MAX(case when communication_type_recID = 14 then e.Description end)
FROM dbo.Contact AS C
LEFT OUTER JOIN dbo.Contact_Communication AS e ON C.Contact_RecID = e.Contact_RecID
AND e.Communication_Type_RecID IN (1,2,4,14)
AND e.Default_Flag = 1
group by C.Company_RecID
, C.Contact_RecID
, C.First_Name
, C.Last_Name
, C.Title
, C.Inactive_Flag
, e.Description

Answer 2

I think UNION might help you. (https://learn.microsoft.com/en-us/sql/t-sql/language-elements/set-operators-union-transact-sql?view=sql-server-2017)
You can try something like this:
select col_1, 'something' as A, '' as B from TableA
union
select col_2, '' as A, 'something' as B from TableA
col_1 and col_2 are actual columns in the table, while A and B are aliases for this extra information.

Answer 3

Without aggregation
select C.Company_RecID
, C.Contact_RecID
, C.First_Name
, C.Last_Name
, C.Title
, C.Inactive_Flag
, e.Description
, e1.Description as EmailAddress
, e2.Description as CellPhone
, e4.Description as DirectNumber
, e14.Description as PersonalCellPhone
FROM dbo.Contact AS C
LEFT OUTER JOIN dbo.Contact_Communication AS e1
ON e1.Contact_RecID = C.Contact_RecID
AND e1.Communication_Type_RecID = 1
AND e1.Default_Flag = 1
LEFT OUTER JOIN dbo.Contact_Communication AS e2
ON e2.Contact_RecID = C.Contact_RecID
AND e2.Communication_Type_RecID = 2
AND e2.Default_Flag = 1
LEFT OUTER JOIN dbo.Contact_Communication AS e4
ON e4.Contact_RecID = C.Contact_RecID
AND e4.Communication_Type_RecID = 4
AND e4.Default_Flag = 1
LEFT OUTER JOIN dbo.Contact_Communication AS e14
ON e14.Contact_RecID = C.Contact_RecID
AND e14.Communication_Type_RecID = 14
AND e14.Default_Flag = 1