SQL String to get data from DB2 I decided to split the SQL Part away from This Question.
Before we get started I need to let you know a critical piece of information: Due to permissions within an offsite database I am NOT allowed to create tables even temporary ones within the database that I am getting the data from.

With that being said: All of the code below works as expected, but I would like a review of it because I know that there has to be a cleaner way of writing the SQL String.

SELECT CONCAT(cfcif#,cfalta) AS Customer_Number,
                 cffna AS First_Name,
                 cfmna AS Middle_Name,
                 COALESCE(NULLIF(cflna,''),cfna1) AS Last_Name,                
                 COALESCE(NULLIF(RTRIM(LTRIM(cfpfa1))|| ' '|| RTRIM(LTRIM(cfpfa2)),''),RTRIM(LTRIM(cfna2),'')|| ' ' || RTRIM(LTRIM(cfna3),'')) AS Street_Address,
                 COALESCE(NULLIF(cfpfcy,''),cfcity) AS Street_City,
                 COALESCE(NULLIF(cfpfst,''),cfstat) AS Street_State,
                 COALESCE(NULLIF(LEFT(cfpfzc, 5), 0), LEFT(cfzip, 5)) AS Street_Zip,
                 CONCAT(RTRIM(LTRIM(cfna2)),RTRIM(LTRIM(cfna3))) AS Mailing_Address,
                 cfcity AS Mailing_City,
                 cfstat AS Mailing_State,
                 LEFT(cfzip, 5) AS Mailing_Zip,
                 NULLIF(cfhpho,0) AS Home_Phone,
                 NULLIF(cfbpho,0) AS Business_Phone,
                 NULLIF(cfssno,0) AS TIN,
                 (CASE 
                    WHEN cfindi = 'Y' THEN '1'
                    WHEN cfindi = 'N' THEN '2'
                   END) AS Customer_Type,
                 (CASE
                    WHEN cfdob7 = 0 THEN NULL
                    WHEN cfdob7 = 1800001 THEN NULL
                    ELSE cfdob7
                  END) AS Date_of_Birth,
                 cfeml1 AS Email_Address
    FROM bhschlp8.jhadat842.cfmast cfmast
    WHERE cfdead = 'N'
    ORDER BY cfcif#
I can't see much wrong with it.  Maybe use BTRIM if on Db2 11.1 or above rather than RTRIM(LTRIM( 
and maybe indent with fewer spaces (e.g. align the first column with the rest), but that is really a matter of style