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

// ExecuteNonQuery 方法的使用
private void button1_Click(object sender, EventArgs e)  //单击事件
{
    try
    {
    SQLHelper.ExecuteNonQuery("insert into T_Age(Name,Age) values(@N,@A)", new SqlParameter("@N", txtLogin.Text.Trim()), new SqlParameter("@A", txtAge.Text.Trim()));
     MessageBox.Show("插入成功！");
    }
    catch (Exception ex)
    {
    MessageBox.Show(string.Format("插入失败！:{0}", ex));           
     return;
    }
}

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

// ExecuteScalar 方法的使用
private void button2_Click(object sender, EventArgs e)  //单击事件
{
   int i = Convert.ToInt32(SQLHelper.ExeccuteScalar("select count(*) T_phone"));
   MessageBox.Show(Convert.ToString(i));
}
//-----------------------------------------------------------------------------

// ExecuteReader 构造 // 不能使用 using
public static SqlDataReader SqlDataReader(string sql, params SqlParameter[] parameters)
{
    string Str = ConfigurationManager.ConnectionStrings["ConnStr"].ConnectionString;
    SqlConnection conn = new SqlConnection(Str);
    conn.Open();
    SqlCommand cmd = conn.CreateCommand();
    cmd.CommandText = sql;
    foreach (SqlParameter par in parameters)
    {
      cmd.Parameters.Add(par);
    }
    SqlDataReader dr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
    cmd.Parameters.Clear();
    return dr;
}

// ExecuteReader 方法的使用
private void button4_Click(object sender, EventArgs e)  //单击事件
{
  SqlDataReader dr = SQLHelper.SqlDataReader_using("select * from T_Age");
  while (dr.Read())
  {
      MessageBox.Show(Convert.ToString(dr["Name"]));  //读取Name字段的值
  }   
}

//-----------------------------------------------------------------------------
// ExecuteDataSet 的构建
public static DataTable ExecuteDataSet(string sql, params SqlParameter[] SqlParmeter)
{
     string Str = ConfigurationManager.ConnectionStrings["ConnStr"].ConnectionString;
     using (SqlConnection conn = new SqlConnection(Str))
     {
     conn.Open();
     SqlCommand cmd = conn.CreateCommand();
     cmd.CommandText = sql;
     foreach (SqlParameter par in SqlParmeter)    //遍历增加 SqlParmeter 参数
     {    
         cmd.Parameters.Add(par);
     }
     DataSet dataset = new DataSet();
     SqlDataAdapter adapter = new SqlDataAdapter(cmd);
     adapter.Fill(dataset);
     return dataset.Tables[0];
     }
}

// ExecuteDataSet 方法的使用
private void button5_Click(object sender, EventArgs e)
{
    DataTable dt = SQLHelper.ExecuteDataSet("select * from T_Age");
    for (int i = 0; i < dt.Rows.Count; i++)
    {
    DataRow row = dt.Rows[i];
    string name =Convert.ToString(row["Name"]);
    MessageBox.Show(name);
    }
}

//-----------------------------------------------------------------------------
注意：SqlDataReader如果用 using 的话，将执行不了，因为在读取数据的时候是在using以外,无法读取
      如下是错误的代码

public static SqlDataReader ExecuteReader_using(string sql, params SqlParameter[] parameters)
{
    string Str = ConfigurationManager.ConnectionStrings["ConnStr"].ConnectionString;
    using (SqlConnection conn = new SqlConnection(Str))
    {
    conn.Open();
    SqlCommand cmd = conn.CreateCommand();
    cmd.CommandText = sql;
    foreach (SqlParameter par in parameters)
    {
        cmd.Parameters.Add(par);
    }
    return cmd.ExecuteReader();
    }
}
//-----------------------------------------------------------------------------

简单的SqlHelper