SQL Crosstab with undetermined columns - sql

Question

I see a lot of similar questions, but almost all of them wind up grouping results as column names (Column names based on results), mine is a more simple list. I don't care if it uses dynamic SQL or not (I'd think it has to).
Please don't tell me I need to restructure the tables, I'm working from a legacy system and don't have that option.
Basically, I just need a list of all valid table "B" entries that match a given record from table "A", in a row.
I don't have any code sample yet, because I'm not seeing a way to set this up correctly.
Table: Customer c
CustID Name
1 Bill Smith
2 Jim Jones
3 Mary Adams
4 Wendy Williams
Table: Debt d
CustID Creditor Balance
1 ABC Loans 245
1 Citibank 815
2 Soprano Financial 74000
3 Citibank 24
3 Soprano Financial 93000
3 Wells Fargo 275
3 Midwestern S&L 2500
4 ABC Loans 1500
4 Fred's Payday Loan 1000
Desired Output:
Name Cred1 Bal1 Cred2 Bal2 Cred3 Bal3 Cred4 Bal4
Bill Smith ABC Loans 245 Citibank 815 (NULL) (NULL) (NULL) (NULL)
Jim Jones Soprano Financial 74000 (NULL) (NULL) (NULL) (NULL) (NULL) (NULL)
Mary Adams Citibank 24 Soprano Finanacial 93000 Wells Fargo 275 Midwestern S&L 2500
Wendy Williams ABC Loans 1500 Fred's Payday Loan 1000 (NULL) (NULL) (NULL) (NULL)
Basically, I probably have to collect some kind of count of the most number of records for any specific "CustomerID", and define the output columns based on that. If this has already been answered, feel free to link and close this out, I did not see this specific scenario when I did my search.

Answer 1

Here is another dynamic approach. We use Row_Number() to create the minimal number of columns.
Example
Declare #SQL varchar(max) = Stuff((Select Distinct ','+QuoteName(concat('Cred',ColNr))
+','+QuoteName(concat('Bal',ColNr))
From (Select ColNr=Row_Number() over (Partition By CustID Order By Creditor) From Debt ) A
Order By 1
For XML Path('')),1,1,'')
Select #SQL = '
Select *
From (
Select C.Name
,B.*
From (
Select *,ColNr=Row_Number() over (Partition By CustID Order By Creditor)
From Debt
) A
Cross Apply (values (concat(''Cred'',ColNr),[Creditor])
,(concat(''Bal'' ,ColNr) ,cast(Balance as varchar(25)))
) B (Item,Value)
Join Customer C on A.CustID=C.CustID
) A
Pivot (max([Value]) For [Item] in (' + #SQL + ') ) p'
--Print #SQL
Exec(#SQL);
Returns
If if Helps, the Generated SQL Looks Like This:
Select *
From (
Select C.Name
,B.*
From (
Select *,ColNr=Row_Number() over (Partition By CustID Order By Creditor)
From Debt
) A
Cross Apply (values (concat('Cred',ColNr),[Creditor])
,(concat('Bal' ,ColNr) ,cast(Balance as varchar(25)))
) B (Item,Value)
Join Customer C on A.CustID=C.CustID
) A
Pivot (max([Value]) For [Item] in ([Cred1],[Bal1],[Cred2],[Bal2],[Cred3],[Bal3],[Cred4],[Bal4]) ) p
Just for the Visualization, the query "feeding" the Pivot generates:

Answer 2

I will guess you are already know how to use cross tab so you only need to prepare your data to use it.
STEP 1: Join both tables:
SELECT c.Name, d.Creditor, d.Balance
FROM Customer c
JOIN Debt d
ON c.CustID = d.CustID
STEP 2: Include a row number to each element related to the customer you are going to use to cross tab
SELECT c.Name, d.Creditor, d.Balance,
ROW_NUMBER() over (PARTITION BY Name ORDER BY creditor) as rndebt_tab
FROM Customer c
JOIN Debt d
ON c.CustID = d.CustID
Now you have:
CustID Creditor Balance rn
1 ABC Loans 245 1
1 Citibank 815 2
2 Soprano Financial 74000 1
3 Citibank 24 1
3 Soprano Financial 93000 2
3 Wells Fargo 275 3
3 Midwestern S&L 2500 4
4 ABC Loans 1500 1
4 Fred's Payday Loan 1000 2
STEP 3: Create the SOURCE for the cross tab
WITH cte as (
<query from step2>
)
SELECT Name,
'CREDITOR_' + RIGHT('000' + CAST(rn AS VARCHAR(3)),3) as cross_tab,
Creditor as Value
FROM cte
UNION all
SELECT Name,
'DEBT_' + RIGHT('000' + CAST(rn AS VARCHAR(3)),3) as cross_tab,
CAST(Balance as VARCHAR(max)) as Value
FROM cte
Now you have:
CustID cross_tab Value
1 CREDITOR_001 ABC Loans
1 CREDITOR_002 Citibank
2 CREDITOR_001 Soprano Financial
3 CREDITOR_001 Citibank
3 CREDITOR_002 Soprano Financial
3 CREDITOR_003 Wells Fargo
3 CREDITOR_004 Midwestern S&L
4 CREDITOR_001 ABC Loans
4 CREDITOR_002 Fred's Payday Loan
1 DEBT_001 245
1 DEBT_002 815
2 DEBT_001 ` 74000
3 DEBT_001 24
3 DEBT_002 93000
3 DEBT_003 275
3 DEBT_004 2500
4 DEBT_001 1500
4 DEBT_002 1000
EDIT: I use CustID instead of Name on the example but too lazy to change now.