SqlHelper类的编写

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Data.SqlClient;
 using System.Data;
 using System.Configuration;

 namespace WpfApplication1
 {
     public class SqlHelper
     {
         private static string connStr = ConfigurationManager.ConnectionStrings["dbConnStr"].ConnectionString;

         public static int ExecuteNonQuery(string sql,params SqlParameter[] parameters)
         {
             using (SqlConnection conn = new SqlConnection(connStr))
             {
                 conn.Open();
                 using (SqlCommand cmd = conn.CreateCommand())
                 {
                     cmd.CommandText = sql;
                     //foreach (SqlParameter parm in parameters)
                     //{
                     //    cmd.Parameters.Add(parm);
                     //}
                     cmd.Parameters.AddRange(parameters);
                     return cmd.ExecuteNonQuery();
                 }
             }
         }

         public static object ExecuteScalar(string sql,params SqlParameter[] parameters)
         {
             using (SqlConnection conn = new SqlConnection(connStr))
             {
                 conn.Open();
                 using (SqlCommand cmd = conn.CreateCommand())
                 {
                     cmd.CommandText = sql;
                     cmd.Parameters.AddRange(parameters);
                     return cmd.ExecuteScalar();
                 }
             }
         }

         /// <summary>
         ///  只用来执行查询结果比较少的sql
         /// </summary>
         /// <param name="sql"></param>
         /// <returns></returns>
         public static DataTable ExecuteDataTable(string sql,params SqlParameter[] parameters)
         {
             DataSet dataSet = new DataSet();
             using (SqlConnection conn = new SqlConnection(connStr))
             {
                 conn.Open();
                 using (SqlCommand cmd = conn.CreateCommand())
                 {
                     cmd.CommandText = sql;
                     cmd.Parameters.AddRange(parameters);
                     SqlDataAdapter adapter = new SqlDataAdapter(cmd);
                     adapter.Fill(dataSet);
                     return dataSet.Tables[];
                 }
             }
         }

     }
 }