ado.net访问数据库的基本用法

放回datatable

  //1:开打数据库的连接
            using (SqlConnection conn = new SqlConnection("server=.;uid=sa;pwd=123456;database=test"))
            {
                conn.Open();
                //2:构建执行sql语句的对象，指定一个sql语句
                using (SqlCommand com = new SqlCommand("select * from UserInfo", conn))
                {
                    //3:执行sql填充到DataTable
                    SqlDataAdapter adapter = new SqlDataAdapter(com);
                    DataTable table = new DataTable();
                    adapter.Fill(table);

                    return table;
                }
            }

返回sqldatareader

 //1:开打数据库的连接
            using (SqlConnection conn = new SqlConnection("server=.;uid=sa;pwd=123456;database=test"))
            {
                conn.Open();
                //2:构建执行sql语句的对象，指定一个sql语句
                using (SqlCommand com = new SqlCommand("select * from UserInfo", conn))
                {
                    //3:执行sql返回SqlDataReader
                    SqlDataReader reader = com.ExecuteReader();
                    //读取(SqlDataReader一行一行的读取)
                    while (reader.Read())
                    {
                        string userAcount = reader[1].ToString();
                        string username = reader["username"].ToString();
                        string userSex = reader["userSex"].ToString();
                    }
                }
            }