Sql Server助手类

/*
 * Author:  joe
 * Create date: 2014.1.17 13:59
 * Description: 数据库助手类
 */
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Configuration;
using System.Data.SqlClient;
using System.Data;

namespace DAL
{
    public class SQLHelper
    {
        string connstr = ConfigurationManager.ConnectionStrings["Constr"].ConnectionString;
        public int ExecuteNonQuery(string sql,CommandType ct, params SqlParameter[] parameters)
        {
            using (SqlConnection conn = new SqlConnection(connstr))
            {
                conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    cmd.CommandType = ct;
                    foreach (SqlParameter parameter in parameters)
                    {
                        cmd.Parameters.Add(parameter);
                    }
                    return cmd.ExecuteNonQuery();
                }
            }
        }
        public object ExecuteScalar(string sql,CommandType ct,params SqlParameter[] parameters)
        {
            using (SqlConnection conn = new SqlConnection(connstr))
            {
                conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    cmd.CommandType = ct;
                    foreach (SqlParameter parameter in parameters)
                    {
                        cmd.Parameters.Add(parameter);
                    }
                    return cmd.ExecuteScalar();
                }
            }
        }
        public DataTable ExecuteDataTable(string sql,CommandType ct, params SqlParameter[] parameters)
        {
            using (SqlConnection conn = new SqlConnection(connstr))
            {
                conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = sql;
                    cmd.CommandType = ct;
                    foreach (SqlParameter parameter in parameters)
                    {

                        cmd.Parameters.Add(parameter);
                    }
                    DataSet ds = new DataSet();
                    SqlDataAdapter adapter = new SqlDataAdapter(cmd);
                    adapter.Fill(ds);
                    return ds.Tables[0];
                }
            }
        }
    }
}