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(nèi)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; 
      } 
    } 
  } 
}