Question

I have a table that contains unfortuantely bad data and I’m trying to filter some out. I am sure that the LName, FName combonation is unique since the data set is small enough to verify.

LName, FName, Email
-----  -----  -----
Smith  Bob    [e-mail]
Smith  Bob    NULL
Doe    Jane   NULL
White  Don    [e-mail]

I would like to have the query results bring back the “duplicate” record that does not have a NULL email, yet still bring back a NULL Email when there is not a duplicate.

E.g.

Smith Bob   [e-mail]
Doe   Jane  NULL
White Don   [e-mail]

I think the solution is similar to Sql, remove duplicate rows by value, but I don’t really understand if the asker’s requirements are the same as mine.

Any suggestions?

Thanks

Answer 1

This drops the null rows if there are any non null values.

SELECT  lname
        , fname
        , MIN(email)
FROM    YourTable
GROUP BY
        lname
        , fname

Test script

DECLARE @Test TABLE (
  LName VARCHAR(32)
  , FName VARCHAR(32)
  , Email VARCHAR(32)
)

INSERT INTO @Test
  SELECT 'Smith', 'Bob', '[e-mail]'
  UNION ALL SELECT 'Smith', 'Bob', 'NULL'
  UNION ALL SELECT 'Doe', 'Jane', 'NULL'
  UNION ALL SELECT 'White', 'Don', '[e-mail]'

SELECT  lname
        , fname
        , MIN(Email)        
FROM    @Test
GROUP BY
        lname
        , fname