语言C#,winform怎么实现combobox联动

Question

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

Answer 1

ado.net里有个什么主从表可以的吧

Answer 2

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!

Answer 3

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。

Answer 4

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

Answer 5

   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？？

Answer 6

我们不直接用sqlDataSource绑定呢？

Answer 7

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";
            }
                
               
           
          
        }

Answer 8

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

Answer 9

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

Answer 10

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

Answer 11

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

Answer 12

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();
}

Answer 13

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