Ado.net 创建DataTable

  /// <summary>

        /// 执行查询语句，返回DataSet

        /// </summary>

        /// <param name="SQLString">查询语句</param>

        /// <returns>DataSet</returns>

        public   DataSet Query(string SQLString, params SqlParameter[] cmdParms)

        {

            using (SqlConnection connection = new SqlConnection(connectionString))

            {

                SqlCommand cmd = new SqlCommand();

                PrepareCommand(cmd, connection, null, SQLString, cmdParms);

                using (SqlDataAdapter da = new SqlDataAdapter(cmd))

                {

                    DataSet ds = new DataSet();

                    try

                    {

                        da.Fill(ds, "ds");

                        cmd.Parameters.Clear();

                    }

                    catch (System.Data.SqlClient.SqlException ex)

                    {

                        throw new Exception(ex.Message);

                    }

                    return ds;

                }

            }

        }

        private   void PrepareCommand(SqlCommand cmd, SqlConnection conn, SqlTransaction trans, string cmdText, SqlParameter[] cmdParms)

        {

            if (conn.State != ConnectionState.Open)

                conn.Open();

            cmd.Connection = conn;

            cmd.CommandText = cmdText;

            if (trans != null)

                cmd.Transaction = trans;

            cmd.CommandType = CommandType.Text;//cmdType;

            if (cmdParms != null)

            {

                foreach (SqlParameter parameter in cmdParms)

                {

                    if ((parameter.Direction == ParameterDirection.InputOutput || parameter.Direction == ParameterDirection.Input) &&

                        (parameter.Value == null))

                    {

                        parameter.Value = DBNull.Value;

                    }

                    cmd.Parameters.Add(parameter);

                }

            }

        }

 

 string connectionString = "Data Source=192.168.42.97;Initial Catalog=DataCompare;User ID=sa;Password=sa";

        public DataTable QueryBigFQCY(string datatype)

        {

            string cmdText = "select   distinct pici from InputData  where and createtime >='2011-09-27 10:40:54.293' order by pici desc";

            DataTable dt = new DataTable();

            SqlParameter[] parm = new SqlParameter[] { new SqlParameter("@datetype", datatype) };

            try

            {

                DataSet ds = Query(cmdText, parm);

                if (ds != null && ds.Tables.Count > 0)

                {

                    dt = ds.Tables[0];

                }

            }

            catch (Exception ex)

            {

                throw new Exception(ex.Message);

            }

            return dt;

        }