public class SqlHelper    {        public static string connstr= ConfigurationManager.ConnectionStrings["Connstr"].ConnectionString;        /// 
        /// 执行增删改        /// 
        ///         ///         /// 
              public static int ExecuteNonQuery(string sql, params SqlParameter[] parameters)        {            using (SqlConnection conn = new SqlConnection(connstr))            {                conn.Open();                using (SqlCommand cmd = new SqlCommand())                {                    cmd.Connection = conn;                    cmd.CommandText = sql;                    cmd.Parameters.AddRange(parameters);                    return cmd.ExecuteNonQuery();                }            }        }        /// 
        /// 返回之后一行一列的数据        /// 
        ///         ///         /// 
              public static object ExecuteScalar(string sql, params SqlParameter[] parameters)        {            using (SqlConnection conn = new SqlConnection(connstr))            {                conn.Open();                using (SqlCommand cmd = new SqlCommand())                {                    cmd.Connection = conn;                    cmd.CommandText = sql;                    cmd.Parameters.AddRange(parameters);                    return cmd.ExecuteScalar();                }            }        }        /// 
        /// 返回查询的表        /// 
        ///         ///         /// 
              public static DataTable ExecuteDataTable(string sql, params SqlParameter[] parameters)        {            using (SqlConnection conn = new SqlConnection(connstr))            {                conn.Open();                using (SqlCommand cmd = new SqlCommand())                {                    cmd.Connection = conn;                    cmd.CommandText = sql;                    cmd.Parameters.AddRange(parameters);                    SqlDataAdapter ada = new SqlDataAdapter(cmd);                    DataSet ds = new DataSet();                    ada.Fill(ds);                    return ds.Tables[0];                }            }        }        /// 
        /// 从数据库查询的数据，如果是DBNull就转换成null        /// 
        ///         /// 
              public static object FromDBNull(object value)        {            if (value == DBNull.Value)            {                return null;            }            else            {                return value;            }        }        /// 
        /// 把数据插入数据库中，如果是null就转换成DBNull        /// 
        ///         /// 
              public static object ToDBNull(object value)        {            if (value == null)            {                return DBNull.Value;            }            else            {                return value;            }        }

这是简单的sqlHelper，保存一下。