Question

I’m reading from a table that is not normalized (not my choice) and trying to map fields within it to another table. Is there a way to do this in one trip? I’m using Microsoft SQL.

TableA:
ID
FieldX1_ID (fixed set of fields that could have been better normalized)
FieldX2_ID
FieldX3_ID

TableB:
FieldX_ID (matches ID's in TableA's fields)
FieldX_Value

I would like the output rows to be:
TableA.ID, TableB.FieldX_Value for TableA.FieldX1_ID, TableB.FieldX_Value for TableA.FieldX2_ID, etc…

Answer 1

You can get the results in two ways. I’m not sure from your description which one you’re after.

To have the results appear in a normalized fashion (you get three rows):

 SELECT TableA.FieldX1_ID AS ID, TableB.FieldX_Value
   FROM TableA JOIN TableB ON TableA.FieldX1_ID = TableB.FieldX_ID
 UNION ALL
 SELECT TableA.FieldX2_ID AS ID, TableB.FieldX_Value
   FROM TableA JOIN TableB ON TableA.FieldX2_ID = TableB.FieldX_ID
 UNION ALL
 SELECT TableA.FieldX3_ID AS ID, TableB.FieldX_Value
   FROM TableA JOIN TableB ON TableA.FieldX2_ID = Table3.FieldX_ID

To have the results appear in de-normalized fashion (you get one row):

 SELECT TableA.FieldX1_ID AS ID1, TableB.FieldX_Value AS Value1,
        TableA.FieldX2_ID AS ID2, TB2.FieldX_Value AS Value2,
        TableA.FieldX3_ID AS ID3, TB3.FieldX_Value AS Value3,
   FROM TableA JOIN TableB ON TableA.FieldX1_ID = TableB.FieldX_ID
               JOIN TableB AS TB2 ON TableA.FieldX2_ID = TB2.FieldX_ID
               JOIN TableB AS TB3 ON TableA.FieldX3_ID = TB3.FieldX_ID