using (SqlCommand cmd = conn.CreateCommand())
 {
      cmd.CommandText = "insert into userInfo(id,userName,userAge,DelFlag)values(11,'赵非',18,0)";
      //设置T-SQL语句
      int num = cmd.ExecuteNonQuery();
      //执行T-SQL语句，并返回受影响的行数
      Console.WriteLine(num);
 }

 using (SqlCommand cmd = conn.CreateCommand())
 {
      cmd.CommandText = "select * from Employee where gender='男' ";
      //查询Employee表中性别为男的所有信息
      label1.Text = cmd.ExecuteScalar().ToString();
      //执行查询，并返回这些信息中的第一行的第一列的数据
 }

using (SqlCommand cmd = conn.CreateCommand())
{
      cmd.CommandText = "select * from employee";
      SqlDataReader reader = cmd.ExecuteReader();
      //执行T-SQL语句，并生成一个SqlDataReader读取器
      while (reader.Read())
      {
         listView1.Items.Add(reader[1].ToString());
      }
      //reader[1]：读取表中第2列的数据
      reader.Close();
}