using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; namespace WindowsFormsApplication2 {   public partial class Form1 : Form   {     public Form1()     {       InitializeComponent();     }     private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)     {     }     private void Form1_Load(object sender, EventArgs e)     {       this.dataGridView1.RowHeadersVisible = false;       this.dataGridView1.AllowUserToAddRows = false;       this.dataGridView1.ReadOnly = true;       this.dataGridView1.SelectionMode = DataGridViewSelectionMode.FullRowSelect;       // this.comboBox1.SelectedIndex =0;       string sql = "select * from student";       DataTable table = SqlManage.TableSelect(sql);       this.dataGridView1.DataSource = table;       comboBox1.Items.Add("學生表");       comboBox1.Items.Add("教師表");     }     private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)     {       string sql = "";       switch (this.comboBox1.SelectedIndex)       {          case 0:           sql = "select id as 學生號,name as 姓名,sage as 年齡 from student";           break;         case 1:           sql = "select t_id as 教師號,t_name as 姓名,T_age as 年齡 from teacher";           break;         default:           break;       }       DataTable table = SqlManage.TableSelect(sql);       this.dataGridView1.DataSource = table;     }   } } 

using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; namespace WindowsFormsApplication2 {   public partial class Form2 : Form   {     public Form2()     {       InitializeComponent();     }     private void button4_Click(object sender, EventArgs e)     {       this.Close();     }     private void button1_Click(object sender, EventArgs e)     {       string sql = string.Format("insert into teacher values('{0}','{1}','{2}')",               this.textBox1.Text, this.textBox2.Text, this.textBox3.Text);       SqlManage.TableChange(sql);     }     private void button2_Click(object sender, EventArgs e)     {       string sql = string.Format("update teacher set ('{0}',''{1}'','{2}')",               this.textBox1.Text, this.textBox2.Text, this.textBox3.Text);       SqlManage.TableChange(sql);     }     private void button3_Click(object sender, EventArgs e)     {       string sql = string.Format("delete from teacher where t_id='{0}'",               this.textBox1.Text);       SqlManage.TableChange(sql);     }     private void Form2_Load(object sender, EventArgs e)     {     }   } } 

using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; namespace WindowsFormsApplication2 {   public partial class Form3 : Form   {     public Form3()     {       InitializeComponent();     }     private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)     {     }     private void Form3_Load(object sender, EventArgs e)     {       this.comboBox1.Enabled = false;       this.comboBox2.Enabled = false;       this.comboBox3.Enabled = false;       this.comboBox4.Enabled = false;       //初始化教師編號       string sql = "select t_id from teacher";       DataTable table = SqlManage.TableSelect(sql);       string t_id;       foreach (DataRow row in table.Rows)       {         t_id = row["t_id"].ToString();         this.comboBox1.Items.Add(t_id);       }       if (table.Rows.Count > 0)       {         this.comboBox1.SelectedIndex = 0;       }       //初始化教師姓名       string sql_name = "select t_name from teacher";       table.Clear();       table = SqlManage.TableSelect(sql_name);       string t_name;       foreach (DataRow row in table.Rows)       {         t_name= row["t_name"].ToString();         this.comboBox2.Items.Add(t_name);       }       if (table.Rows.Count > 0)       {         this.comboBox2.SelectedIndex = 0;       }       //初始化學生       string sql_id = "select id from student";       table.Clear();       table = SqlManage.TableSelect(sql_id);       string s_id;       foreach (DataRow row in table.Rows)       {         s_id = row["id"].ToString();         this.comboBox3.Items.Add(s_id);       }       if (table.Rows.Count > 0)       {         this.comboBox3.SelectedIndex = 0;       }       //初始化學生       string sql_sname = "select name from student";       table.Clear();       table = SqlManage.TableSelect(sql_sname);       string t_sname;       foreach (DataRow row in table.Rows)       {         t_sname = row["name"].ToString();         this.comboBox4.Items.Add(t_sname);       }       if (table.Rows.Count > 0)       {         this.comboBox4.SelectedIndex = 0;       }     }     private void button2_Click(object sender, EventArgs e)     {       this.Close();     }     private void button1_Click(object sender, EventArgs e)     {       string sql = "";       if (this.radioButton1.Checked)       {         sql = string.Format("select t_id as 教師編號,t_name as 教師姓名,t_age as 年齡 from teacher where t_id = '{0}'",           this.comboBox1.Text);       }       else if (this.radioButton2.Checked)       {         sql = string.Format("select t_id as 教師編號,t_name as 教師姓名,t_age as 年齡 from teacher where t_name = '{0}'",           this.comboBox2.Text);       }       else if (this.radioButton3.Checked)       {         sql = string.Format("select id as 學生編號,name as 學生姓名,sage as 年齡 from student where id = '{0}'",           this.comboBox3.Text);       }       else if (this.radioButton4.Checked)       {         sql = string.Format("select id as 學生編號,name as 學生姓名,sage as 年齡 from student where name = '{0}'",           this.comboBox4.Text);       }       DataTable table = SqlManage.TableSelect(sql);       if (table.Rows.Count > 0)       {         this.dataGridView1.DataSource = table;       }       else       {         MessageBox.Show("沒有相關內容");       }     }     private void radioButton1_CheckedChanged(object sender, EventArgs e)     {       if (this.radioButton1.Checked)       {         this.comboBox1.Enabled = true;       }       else       {         this.comboBox1.Enabled = false;       }     }     private void radioButton2_CheckedChanged(object sender, EventArgs e)     {       if (this.radioButton2.Checked)       {         this.comboBox2.Enabled = true;       }       else       {         this.comboBox2.Enabled = false;       }     }     private void radioButton3_CheckedChanged(object sender, EventArgs e)     {       if (this.radioButton3.Checked)       {         this.comboBox3.Enabled = true;       }       else       {         this.comboBox3.Enabled = false;       }     }     private void radioButton4_CheckedChanged(object sender, EventArgs e)     {       if (this.radioButton4.Checked)       {         this.comboBox4.Enabled = true;       }       else       {         this.comboBox4.Enabled = false;       }     }   } }