Question

I have a table with data like the following:

ID    Mfgr    Primary_Mfgr
a1    Acme    P
a1    Bcme    S
a1    Ccme    S
b1    Acme
b1    Bcme
c1    Acme    S
c1    Bcme
d1    Acme
d1    Bcme

I need to create a select statement that will, based on ID return the record with a P as the Primary_Mfgr, if there is no P record, then return the blank record, if those don’t exist then return the first S record. In all cases, if there are duplicates return the first result.

Therefore, using the above data I would expect to return the following from four different queries:

Query for a1:

a1    Acme    P

Query for b1:

b1    Acme

Query for c1:

c1    Bcme

Query for d1:

d1    Acme

In every case I need to return just one record. I’m not sure how I would structure to do this. I can easily get back all the ‘a1’ records for example, but I’m not sure how I would write a query that can take a parameter for ID and still return the correct single record in all circumstances. I’m using SQL Server 2008 R2.

Answer 1

You can just order by the Primary_Mfgr column with a case statement and then select the top 1

SELECT TOP 1 *
FROM Table1
WHERE ID = @ID
ORDER BY 
    CASE Primary_Mfgr 
        WHEN 'P' THEN 1
        WHEN ''  THEN 2
        ELSE 3
    END