How to concatenate columns properly using T-SQL?

Question

I have a address in more than one column in a table.

SELECT FirstName, LastName, StreetAddress, City, Country, PostalCode 
FROM Client

I a

Answer 1

When you concatenate anything with a null, it returns null. So I'm trying to concatenate a comma with the given column value and if that expression returns null, I use Coalesce to return an empty string. At the end, if I get a value, the entire result will start with a comma. So I remove that comma using the Stuff function.

Select Stuff(
    Coalesce(',' + FirstName,'')
    + Coalesce(',' + LastName,'')
    + Coalesce(',' + StreetAddress,'')
    + Coalesce(',' + City,'')
    + Coalesce(',' + Country,'')
    + Coalesce(',' + PostalCode ,'')
    , 1, 1, '')
From Client

If you only want the address, then obviously you would only include those columns:

Select FirstName, LastName
    , Stuff(
        Coalesce(',' + StreetAddress,'')
        + Coalesce(',' + City,'')
        + Coalesce(',' + Country,'')
        + Coalesce(',' + PostalCode ,'')
    , 1, 1, '')
From Client