语言C#,winform怎么实现combobox联动

[ghostql]

比如数据库中有两个表，一个系部表depart,字段departId,departname一个专业表major，字段majorId,departId,majorname
怎么实现选一个系部的时候，另一个COMBOBOX里面是现实的是与这系部有关的专业
今天弄很久了，都没弄明白

[ghostql]

[Quote=引用 2 楼 itliyi 的回复:]
分数少了。。。
[/Quote]
那你要多少分，写的正确就给你

[dalu007]

在第一系部COMBOBOX里,定义一个SelectedIndexChanged事件,
在事件中写上 取第二个COMBBOX的数据源代码,重新赋值第二个COMBOBOX的数据源
我是这样弄的,更直接点!

[Flyingdragon168]

同意樓上。
在第一個Combox，當選擇的內容變化時，再加載第二個Combox的數據，條件則是第一個Combox的變換後的內容。

[flyfly2008]

同意4楼的，要在第一个COMBOX的SelectedIndexChanged事件，再去搜索你要第二个COMBOX事件

[ghostql]

   private void Form1_Load(object sender, EventArgs e)
        {
            SqlConnection con = new SqlConnection(conn);
            con.Open();
            SqlCommand cmd = new SqlCommand("select * from department",con);
            SqlDataAdapter sda = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            sda.Fill(dt);
            con.Close();
            comboBox1.DataSource = dt;
            comboBox1.DisplayMember = "department";
            comboBox1.ValueMember = "departmentId";

        }

        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            
                 SqlConnection con = new SqlConnection(conn);
                 con.Open();
                 SqlCommand cmd = new SqlCommand("select * from major where departmentId='"+comboBox1.SelectedValue.ToString()+"'",con);
                 SqlDataAdapter sda = new SqlDataAapter(cmd);
                 DataTable dt = new DataTable();
                 
                     comboBox2.DataSource = dt;
                     comboBox2.DisplayMember = "major";
                     comboBox2.ValueMember = "majorId";
               
           
         
        }

为什么这样就不对呢？？

[ITtaowmdj]

我们不直接用sqlDataSource绑定呢？

[ghostql]

问题已解决，自己好不容易想出来，居然没人帮

代码如下

private void Form1_Load(object sender, EventArgs e)
        {
            SqlConnection con = new SqlConnection(conn);
            con.Open();
            SqlCommand cmd = new SqlCommand("select * from department",con);           
            SqlDataAdapter sda = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            sda.Fill(dt);
            con.Close();
            comboBox1.DataSource = dt;
            comboBox1.DisplayMember = "department";
            comboBox1.ValueMember = "departmentId";

        }

        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (comboBox1.SelectedIndex>-1)
            {
                DataRowView drv = (DataRowView)comboBox1.SelectedItem;
                int id = Convert.ToInt32(drv.Row["departmentId"].ToString());
                SqlConnection con = new SqlConnection(conn);
                con.Open();
                SqlCommand cmd = new SqlCommand("select * from major where departmentId='" + id + "'", con);
                SqlDataAdapter sda = new SqlDataAdapter(cmd);             
                DataTable dt = new DataTable();
                sda.Fill(dt);
                comboBox2.DataSource = dt;
                comboBox2.DisplayMember = "major";
                comboBox2.ValueMember = "majorId";
            }
                
               
           
          
        }

[aotian798]

晕 来完了 接分

[lzhdim]

呵呵，这个不挺简单的么，基本控件的使用问题。。。

[ghostql]

现在我要实现3个combobox联动又出现问题了，像我这样写又不对了
怎么改进

 private void cmbDpt_SelectedIndexChanged(object sender, EventArgs e)
        {


            if (cmbDpt.SelectedIndex > -1)
            {
                DataRowView drv = (DataRowView)cmbDpt.SelectedItem;
                int id = Convert.ToInt32(drv.Row["departmentId"].ToString());
                DataTable dt = new SQLHelper().getResultToDataTable("select * from major where departmentId='" + id + "'");
                cmbMajor.DataSource = dt;
                cmbMajor.DisplayMember = "major";
                cmbMajor.ValueMember = "majorId";
            }




        }

        private void cmbMajor_SelectedIndexChanged(object sender, EventArgs e)
        {
          
                DataRowView drv = (DataRowView)cmbMajor.SelectedItem;
                int id = Convert.ToInt32(drv.Row["majorId"].ToString());
                DataTable dt = new SQLHelper().getResultToDataTable("select * from class where majorId='" + id + "'");
                cmbClass.DataSource = dt;
                cmbClass.DisplayMember = "className";
                cmbClass.ValueMember = "classId";
            

        }

这个是在第2个COMBOBOX那SelectedIndexChanged事件里，写的，可是当第一个动的时候要怎么实现第3个也跟着动了

[ghostql]

没人知道吗？？

[wuyq11]

在cmbDpt_SelectedIndexChanged里Items.Clear();
在cmbMajor_SelectedIndexChanged里再绑定第三个或查询数据直接绑定

[cc_net]

COMBOBOX.SelectedIndexChanged +=

想多少个联动，想干什么都行，只要吧SelectedIndexChanged时要做的动作都加上就行了

[flyerwing]

如十二楼

[AndyGu_Rover]

像LZ这样写不把人累死啊

[wu8862889]

建议你找个城市级联的例子看下

[辉太郎]

private void cmbDpt_SelectedIndexChanged(object sender, EventArgs e)
{
	bindMajor();
	bindClass();
}
private void cmbMajor_SelectedIndexChanged(object sender, EventArgs e)
{
	bindClass();
}

[zxforben111]

[Quote=引用 18 楼 wu8862889 的回复:]
建议你找个城市级联的例子看下
[/Quote]

有道理，要找个好点的办法。
如：

private void cmbDpt_SelectedIndexChanged(object sender, EventArgs e)
{
    bindMajor();
    bindClass();
}
private void cmbMajor_SelectedIndexChanged(object sender, EventArgs e)
{
    bindClass();
}

[jungeuichul]

给你一个年月日关联的例子吧
private void cmbYear_SelectedIndexChanged(object sender, EventArgs e)
{
if (this.cmbYear.Text != "----")
{
this.cmbMonth.Enabled = true;
int year, month, day = 0;

year = Convert.ToInt32(this.cmbYear.Text.ToString());
if (this.cmbMonth.Text.ToString() == "" || this.cmbMonth.Text.ToString() == "--")
{
month = Convert.ToInt32(DateTime.Now.Month.ToString());
}
else
{
month = Convert.ToInt32(this.cmbMonth.Text.ToString());
}


day = DateTime.DaysInMonth(year, month);
this.cmbDay.Items.Clear();
this.cmbDay.Items.Add("--");
for (int i = 1; i <= day; i++)
{
if (i < 10)
{
this.cmbDay.Items.Add('0' + i.ToString());
}
else
{
this.cmbDay.Items.Add(i.ToString());
}
}
if (this.cmbMonth.Text.ToString() == "" || this.cmbMonth.Text.ToString() == "--")
{
this.cmbDay.Text = "--";
}
else
{
if (DateTime.Now.Day.ToString().Length == 1)
{
this.cmbDay.Text = '0' + DateTime.Now.Day.ToString();
}
else
{
this.cmbDay.Text = DateTime.Now.Day.ToString();
}
}
}
else
{
this.cmbMonth.Text = "--";
this.cmbMonth.Enabled = false;
this.cmbDay.Text = "--";
this.cmbDay.Enabled = false;
}
}

private void cmbMonth_SelectedIndexChanged(object sender, EventArgs e)
{
if (this.cmbMonth.Text != "--")
{
this.cmbDay.Enabled = true;
int year, month, day = 0;

year = Convert.ToInt32(this.cmbYear.Text.ToString());
if (this.cmbMonth.Text.ToString() == "")
{
month = Convert.ToInt32(DateTime.Now.Month.ToString());
}
else
{
month = Convert.ToInt32(this.cmbMonth.Text.ToString());
}


day = DateTime.DaysInMonth(year, month);
this.cmbDay.Items.Clear();
this.cmbDay.Items.Add("--");
for (int i = 1; i <= day; i++)
{
if (i < 10)
{
this.cmbDay.Items.Add('0' + i.ToString());
}
else
{
this.cmbDay.Items.Add(i.ToString());
}
}
if (DateTime.Now.Day.ToString().Length == 1)
{
this.cmbDay.Text = '0' + DateTime.Now.Day.ToString();
}
else
{
this.cmbDay.Text = DateTime.Now.Day.ToString();
}
}
else
{
this.cmbDay.Text = "--";
this.cmbDay.Enabled = false;
}
}

当选择年为----时，月日都为--，当选择月为--时，日为--，当选择年月为具体值时，日加载的是对应的天数和--，你可以这样借鉴一下三个combox关联的问题

[bjtiantian]

[Quote=引用 15 楼 cc_net 的回复:]
COMBOBOX.SelectedIndexChanged +=

想多少个联动，想干什么都行，只要吧SelectedIndexChanged时要做的动作都加上就行了
[/Quote]
这样做没问题，OK