Q:

Need to join two strings if both contain values, or return one value if first is NULL

enter code hereIn my SQL Server database I have my address information for the subNumber (e.g. Unit 802) and the streetNumber (e.g. 242 Elizabeth Street) stored separately.
I need to display these as one (i.e. 802/242 Elizabeth Street) if the subNumber contains a value, otherwise just return the streetNumber if it does not.
I've been working toward a solution using IF ELSE and a foreach loop after accessing the data through LINQ - but I'm stuck after the point where I have completed the loop. I would also be happy to do this with a SELECT Stored Procedure in SQL - open to suggestions!
DataClassesDataContext dc = new DataClassesDataContext();

var recent = from p in dc.Properties
             orderby p.modtime descending
             where p.status == "Current"
             select new
             {
                 rsub = (p.subNumber).ToString(),
                 rnumber = (p.streetNumber).ToString(),
                 rstreet = p.street,
                 rsuburb = p.suburb,
                 rurl = p.propertyURL,
             };

foreach (var home in recent)
{
    if (string.IsNullOrEmpty(home.rsub))
    {
        string rnum = home.rnumber;
    }
    else
    {
        string rnum = home.rsub + "/" + home.rnumber;
    }
}

recentrepeater.DataSource = recent;
recentrepeater.DataBind();

Yahia gave the best option in c# - this is the SQL solution I have finally ended up with:
ALTER PROCEDURE GetPropertyShort

AS
SELECT TOP 5 ISNULL(convert(varchar(5), subNumber) + '/' + convert(varchar(5), streetNumber), convert(varchar(5), streetNumber)) as Number, street, suburb, propertyURL, modtime
FROM Property
ORDER BY modtime DESC

A:

try
var recent = from p in dc.Properties
        orderby p.modtime descending
        where p.status == "Current"
        select new
       {
            rsub = (p.subNumber).ToString(),
            rnumber = (p.streetNumber).ToString(),
            rnum = string.IsNullOrEmpty((p.subNumber).ToString()) ? (p.streetNumber).ToString() : (p.subNumber).ToString() + "/" + (p.streetNumber).ToString(),
            rstreet = p.street,
            rsuburb = p.suburb,
            rurl = p.propertyURL,
        };

