Obtaining a Single Value from a Database


You may need to return database information that is simply a single value rather than in the form of a table or data stream. For example, you may want to return the result of an aggregate function such as COUNT(*), SUM(Price), or AVG(Quantity). The Command object provides the capability to return single values using the ExecuteScalar method. The ExecuteScalar method returns, as a scalar value, the value of the first column of the first row of the result set.

The following code example inserts a new value in the database using a SqlCommand. The ExecuteScalar method is used to return the identity column value for the inserted record.

static public int AddProductCategory(string newName, string connString)
    Int32 newProdID = 0;
    string sql =
        "INSERT INTO Production.ProductCategory (Name) VALUES (@Name); "
        + "SELECT CAST(scope_identity() AS int)";
    using (SqlConnection conn = new SqlConnection(connString))
        SqlCommand cmd = new SqlCommand(sql, conn);
        cmd.Parameters.Add("@Name", SqlDbType.VarChar);
        cmd.Parameters["@name"].Value = newName;
            newProdID = (Int32)cmd.ExecuteScalar();
        catch (Exception ex)
    return (int)newProdID;