Array or object from SQL req

Hello guys !
I am just starting to learn C# (i am from PHP) and i need a litle help to understand how to work with SQL query
I explain what i want to do with php code:

Code:

$req = $bdd->prepare("SELECT count(`steamid`) FROM users WHERE `steamid` = :id");
$req->execute(array(':id' => $usersteamid));
$data = $req->fetch(PDO::FETCH_ASSOC);
$count = $data['count'];

i block here :

Code:

$data = $req->fetch(PDO::FETCH_ASSOC);
$count = $data['count'];

with Csharp i make this code but if some one can help me

Code:

            var    sqlLibrary = Interface.Oxide.GetLibrary<Core.MySql.Libraries.MySql>();
            var    sqlConnection = sqlLibrary.OpenDb("localhost", 3306, "rust", "rust", "rust", this);
            var sqlQuery = "SELECT count(`steamid`) as count FROM users where `steamid` = @0";
            var selectCommand = Oxide.Core.Database.Sql.Builder.Append(sqlQuery, player.userID.ToString());            sqlLibrary.Query(selectCommand, sqlConnection, list =>
            {                var newString = new StringBuilder();
                newString.AppendLine(" count");                foreach (var entry in list)
                {
                    newString.AppendFormat(" {0}", entry["count"]);
                }                Puts(newString.ToString());
            });