using System;
 using System.Data;
 using System.Data.SqlClient;
 public class Helper
 {
     public static void Main()
     {
         //连接字符串
         string strcon = "server = .;database = blog;uid = sa;pwd = 1";
         SqlHelper helper = new SqlHelper(strcon);
         //表employee中有neme(varchar(20)),age(int),sex(bit)三个字段;
         string sql = "select * from employee";
         SqlDataReader reader = helper.Reader(sql,null);
         using (reader)
         {
             while (reader.Read())
             {
                 Console.WriteLine(reader["name"].ToString());
             }
         }
         /*string sql = "insert into employee values(@name,@age,@sex)";
         SqlParameter[] ps = new SqlParameter[]
         {
             new SqlParameter("@name",SqlDbType.VarChar,20),
             new SqlParameter("@age",SqlDbType.Int),
             new SqlParameter("@sex",SqlDbType.Int)
         };
            
             ps[0].Value = "张宇";
             ps[1].Value = 40;
             ps[2].Value = 1;
             helper.ExecuteNonQuery(sql,ps);*/
     }
 }
 public class SqlHelper
 {
     private SqlConnection con = null;
     private SqlCommand cmd = null;
     public SqlHelper (string strcon)
     {
         con = new SqlConnection(strcon);
         cmd = new SqlCommand();
         cmd.Connection = con;
     }
     //执行初始化Command对象
     private void PreparedCommand(string sql,params SqlParameter[]param)
     {
         cmd.CommandText = sql;
         //清空Parameteras中的对象
         cmd.Parameters.Clear();
         if (param!=null)
         {
             foreach (SqlParameter p in param)
             {
                 cmd.Parameters.Add(p);
             }
         }
         con.Open();
     }
     /*执行非查询语句*/
     //有参数
     public int ExecuteNonQuery(string sql,params SqlParameter[] param)
     {
         PreparedCommand(sql,param);
         int i = cmd.ExecuteNonQuery();
         Close();
         return i;
     }
     //无参数
     public int ExecuteNonQuery(string sql)
     {
         PreparedCommand(sql,null);
         int i = cmd.ExecuteNonQuery();
         Close();
         return i;
     }
     /*执行查询语句*/
     //有参数
     public SqlDataReader Reader(string sql,params SqlParameter[] param)
     {
         PreparedCommand(sql,param);
         return cmd.ExecuteReader();
     }
     //无参数
     public SqlDataReader Reader(string sql)
     {
         PreparedCommand(sql,null);
         return cmd.ExecuteReader();
        
     }
 
     public void Open()
     {
         con.Open();
     }
     public void Close()
     {
         cmd.Dispose();
         con.Close();
     }
 }