封装SQLHelper

//
//	author:	agile
//	datetime:5/29/2011 8:59:13 AM
//	class:	SQLHelper
//
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;
using System.Configuration;
using System.Data;

namespace SqlHelper

{
    class SQLHelper
    {
        public static int ExecuteNonQuery(string sql,params SqlParameter[] parameters) 
        {
            string conn = ConfigurationManager.ConnectionStrings["conn"].ConnectionString;
            using (SqlConnection strconn = new SqlConnection(conn)) 
            {
                strconn.Open();
                using (SqlCommand cmd = strconn.CreateCommand()) 
                {
                    cmd.CommandText = sql;
                    foreach (SqlParameter parameter in parameters)
                    {
                        cmd.Parameters.Add(parameter); 
                    }
                    return cmd.ExecuteNonQuery();
                }
            }

        }
        public static object ExecuteScalar(string sql, params SqlParameter[] parameters) 
        {
            string conn = ConfigurationManager.ConnectionStrings["conn"].ConnectionString;
            using (SqlConnection strconn = new SqlConnection(conn))
            {
                strconn.Open();
                using (SqlCommand cmd = strconn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    foreach (SqlParameter parameter in parameters)
                    {
                        cmd.Parameters.Add(parameter);
                    }
                    return cmd.ExecuteScalar();
                }
            }

        }
        public static DataTable ExecuteDataTable(string sql, params SqlParameter[] parameters)
        {
            string conn = ConfigurationManager.ConnectionStrings["conn"].ConnectionString;
            using (SqlConnection strconn = new SqlConnection(conn))
            {
                strconn.Open();
                using (SqlCommand cmd = strconn.CreateCommand())
                {
                    cmd.CommandText = sql;
                     foreach (SqlParameter parameter in parameters)
                    {
                        cmd.Parameters.Add(parameter);
                    }
                    DataSet dataset = new DataSet();
                    SqlDataAdapter adapter = new SqlDataAdapter(cmd);
                    adapter.Fill(dataset);
                    return dataset.Tables[0];
                      

                 }             
            }
           

        }
    }
}

使用：

  string name = Convert.ToString(SQLHelper.ExecuteScalar("select name from T_persons where id=@id", new SqlParameter("id", 20)));