T SQL Conditional String Concatenation

Question

Have a 5 columns of address data. I need to concatenate these fields into a single address with spaces in between the values if they exist. If the column has a null value I should skip it and not enter any space.

select 
        case 
            when street_number != '' THEN (cast(street_number as int)) 
        end as street_number,
        case
            when street_ext != '' then
                    case
                        when street_ext = 50 then '1/2'
                    end
        end as street_ext,
        case
            when street_direct ! = '' then street_direct
        end as street_direct,
        case
            when site_street ! = '' then site_street
        end as site_street,
        case
            when site_address ! = '' then site_address
        end as site_address
    from parcel 

what I'd like to do is have a variable and assign it to the value of the first column street_number, then when I move on to the next column, street_ext, if it isn't null I'd like to check to see if the variable is null and if not, append a space and the value...and so on down the road.

I'm rusty as hell and could use a push in the right direction.

Thanks everyone.

Answer 1

Use the "+" to concatenate strings in TSQL:

SELECT CASE 
         WHEN LEN(p.street_number) > 0 THEN p.street_number + ' ' 
         ELSE '' 
       END +
       CASE 
         WHEN p.street_ext = 50 THEN '1/2'
         WHEN LEN(p.street_ext) > 0 THEN ''
         ELSE p.street_ext
       END + ' ' +
       CASE 
         WHEN LEN(p.street_direct) > 0 THEN p.street_direct + ' '
         ELSE ''
       END + 
       CASE 
         WHEN LEN(p.site_street) > 0 THEN p.site_street + ' '
         ELSE ''
       END  + 
       CASE 
         WHEN LEN(p.site_address) > 0 THEN p.site_address + ' '
         ELSE ''
       END AS full_address
FROM PARCEL p

The LEN function returns zero if the string value is NULL, or a zero length string.