day23C#DataReader与ComboBox的运用

今日份课堂作业&＃xff0c;连接数据库&＃xff0c;创建下拉列表控件&＃xff0c;读取数据库里的数据并显示在下拉列表控件上

效果图如下&＃xff1a;


学生姓名后面的ComboBox命名为cboStu&＃xff0c;年级后的为cboGrade。
代码如下&＃xff1a;

private void Form1_Load(object sender, EventArgs e){string connString &＃61; "Data Source&＃61;.;Initial Catalog&＃61;MySchool;Uid&＃61;sa;Pwd&＃61;123456";SqlConnection connection &＃61; new SqlConnection(connString);string sql &＃61; "select StudentName from Student";SqlCommand command &＃61; new SqlCommand(sql, connection);string studentname &＃61; "";try{connection.Open();SqlDataReader dataReader &＃61; command.ExecuteReader();while (dataReader.Read()){studentname &＃61; (string)dataReader[0];cboStu.Items.Add(studentname);Console.WriteLine((string)dataReader["StudentName"]);}dataReader.Close();}catch(Exception ex){MessageBox.Show("操作数据库出错辽");Console.WriteLine(ex.Message);}finally{connection.Close();}string sql1 &＃61; "select GradeName from Grade";SqlCommand command1 &＃61; new SqlCommand(sql1, connection);string gradename &＃61; "";try{connection.Open();SqlDataReader dataReader1 &＃61; command1.ExecuteReader();while (dataReader1.Read()){gradename &＃61; (string)dataReader1[0];cboGrade.Items.Add(gradename);Console.WriteLine((string)dataReader1["GradeName"]);}dataReader1.Close();}catch(Exception ex1){MessageBox.Show("操作数据库出错辽辽");Console.WriteLine(ex1.Message);}finally{connection.Close();}}


试了几次只打开一次数据库连接&＃xff0c;后来发现要分开写&＃xff0c;得分别打开数据库连接创建command对象等等。

想要数据库文件的可以在我发的资源里下载→→SqlServer数据库 MySchool资源mdf文件