Update Useful-script-snippets.md

[Daandamhuis]

This part prevents the script from crashing if other sources, like Excel or Json, are present in the model.

if (p.Expression.Contains("Source = Sql.Database"))
{
    var oldServer = "\"" + GetServer(p.Expression) + "\"";
    var oldDatabase = "\"" + GetDatabase(p.Expression) + "\"";
    p.Expression = p.Expression.Replace(oldServer, server).Replace(oldDatabase, database);
}

[otykier]

Thanks for your contribution!