SqlHelper的编写

static class SqlHelper
{
    private static string strConn = ConfigurationManager.ConnectionStrings["连接字符串的名字"].ConnectionString;
    public static int ExecuteNonQuery(string sql,params SqlParameter[] parameters)
    {
        using(SqlConnection conn = new SqlConnection(strConn))
        {
            conn.Open();
            using(SqlCommand cmd = conn.CreateCommand())
            {
                cmd.CommandText = sql;
                cmd.Parameters.AddRange(parameters);
                return cmd.ExecuteNonQuery();
            }
        }
    }
    
    public static Object ExecuteScalar(string sql,params SqlParameter[] parameters)
    {
        using(SqlConnection conn = new SqlConnection(strConn))
        {
            conn.Open();
            using(SqlCommand cmd = conn.CreateCommand())
            {
                cmd.CommandText = sql;
                cmd.Parameters.AddRange(parameters);
                return cmd.ExecuteScalar();
            }
        }
    }
    public static DataTable ExecuteDataTable(string sql,params SqlParameter[] parameters)
    {
        using(SqlConnection conn = new SqlConnection(strConn))
        {
            conn.Open();
            using(SqlCommand cmd = conn.CreateCommand())
            {
                cmd.CommandText = sql;
                cmd.Parameters.AddRange(parameters);
                SqlDataAdapter adapter = new SqlDataAdapter(cmd);
                DataSet dataset = new DataSet();
                adapter.Fill(dataset);
                return dataset.Tables[0];
            }
        }
    }
}