Question

I’m trying to extract some data from a third party system which uses an SQL Server database. The DB structure looks something like this:

Order

OrderID   OrderNumber
   1         OX101 
   2         OX102

OrderItem

OrderItemID  OrderID   OptionCodes
     1          1      12,14,15
     2          1      14
     3          2      15

Option

OptionID   Description
    12      Batteries
    14      Gift wrap
    15      Case
[etc.]

What I want is one row per order item that includes a concatenated field with each option description. So something like this:

OrderItemID   OrderNumber   Options
    1            OX101      Batteries\nGift Wrap\nCase
    2            OX101      Gift Wrap
    3            OX102      Case

Of course this is complicated by the fact that the options are a comma separated string field instead of a proper lookup table. So I need to split this up by comma in order to join in the options table, and then concat the result back into one field.

At first I tried creating a function which splits out the option data by comma and returns this as a table. Although I was able to join the result of this function with the options table, I wasn’t able to pass the OptionCodes column to the function in the join, as it only seemed to work with declared variables or hard-coded values.

Can someone point me in the right direction?

Answer 1

I would use a splitting function (here’s an example) to get individual values and keep them in a CTE. Then you can join the CTE to your table called “Option”.

SELECT * INTO #Order
FROM (
  SELECT 1 OrderID, 'OX101' OrderNumber UNION SELECT 2, 'OX102'
) X;

SELECT * INTO #OrderItem
FROM (
  SELECT 1 OrderItemID, 1 OrderID, '12,14,15' OptionCodes
  UNION
  SELECT 2, 1, '14'
  UNION
  SELECT 3, 2, '15'
) X;

SELECT * INTO #Option
FROM (
  SELECT 12 OptionID, 'Batteries' Description
  UNION
  SELECT 14, 'Gift Wrap'
  UNION
  SELECT 15, 'Case'
) X;

WITH N AS (
  SELECT I.OrderID, I.OrderItemID, X.items OptionCode
  FROM #OrderItem I CROSS APPLY dbo.Split(OptionCodes, ',') X
)
SELECT Q.OrderItemID, Q.OrderNumber,
       CONVERT(NVarChar(1000), (
         SELECT T.Description + ','
         FROM N INNER JOIN #Option T ON N.OptionCode = T.OptionID
         WHERE N.OrderItemID = Q.OrderItemID
         FOR XML PATH(''))
       ) Options
FROM (
  SELECT N.OrderItemID, O.OrderNumber
  FROM #Order O INNER JOIN N ON O.OrderID = N.OrderID
  GROUP BY N.OrderItemID, O.OrderNumber) Q

DROP TABLE #Order;
DROP TABLE #OrderItem;
DROP TABLE #Option;