日期与地区的三级联动

地区的三级联动：

数据库中有地区名，地区编号，上级编号；

public Form1()
{
InitializeComponent();
chinastatesdata chi = new chinastatesdata();
List<chinastates> cl = chi.select(0001);
comboBox1.DataSource = cl;
comboBox1.DisplayMember = "areaname";
comboBox1.ValueMember = "areacode";
}

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
//chinastatesdata chi = new chinastatesdata();
//int a = 11;
//if (comboBox1.Text.Length < 20)
//{
// a = chi.se(comboBox1.Text);
//}
chinastates c = comboBox1.SelectedItem as chinastates;
List<chinastates> cl = new chinastatesdata().select(c.areacode);
comboBox2.DataSource = cl;
comboBox2.DisplayMember = "areaname";
comboBox2.ValueMember = "areacode";
}

private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
{
chinastates c = comboBox2.SelectedItem as chinastates;
List<chinastates> cl = new chinastatesdata().select(c.areacode);
comboBox3.DataSource = cl;
comboBox3.DisplayMember = "areaname";
comboBox3.ValueMember = "areacode";
}

public List<chinastates> select(int a)
{
List<chinastates> cl = new List<chinastates>();
com.CommandText = "select * from chinastates where parentareacode= @a";
com.Parameters.Clear();
com.Parameters.AddWithValue("@a", a);
con.Open();
SqlDataReader dr = com.ExecuteReader();
if (dr.HasRows)
{
while (dr.Read())
{
chinastates c = new chinastates();
c.areacode = Convert.ToInt32(dr["areacode"]);
c.areaname = dr["areaname"].ToString();
cl.Add(c);
}
}
con.Close();
return cl;
}

--------------------------------

日期的三级联动：

List<int> i = new List<int>();
for (int x = DateTime.Now.Year; x > 1950; x--)
{
i.Add(x);
}
comboBox2.DataSource = i;

List<int> ii = new List<int>();
for(int x = 1; x < 13; x++)
{
ii.Add(x);
}
comboBox3.DataSource = ii;

List<int> iii = new List<int>();
iii.Add(1);
comboBox4.DataSource = iii;

private void textBox2_Enter(object sender, EventArgs e)
{
if (textBox2.ForeColor == Color.Red)
{
textBox2.Text = "";
textBox2.ForeColor = Color.Black;
}
}

private void textBox3_Enter(object sender, EventArgs e)
{
if (textBox3.ForeColor == Color.Red)
{
textBox3.Text = "";
textBox3.ForeColor = Color.Black;
}
}

private void comboBox4_Enter(object sender, EventArgs e)
{
int n = Convert.ToInt32(comboBox2.Text);
int y = Convert.ToInt32(comboBox3.Text);
if (y == 2 && ((n % 4 == 0 && n % 100 != 0) || n % 400 == 0))
{
List<int> i = new List<int>();
for (int x = 1; x <= 29; x++)
{
i.Add(x);
}
comboBox4.DataSource = i;
}
if (y == 2 && (n % 4 != 0 || (n % 100 == 0 && n % 400 != 0)))
{
List<int> i = new List<int>();
for (int x = 1; x <= 28; x++)
{
i.Add(x);
}
comboBox4.DataSource = i;
}
if (y == 1 || y == 3 || y == 5 || y == 7 || y == 8 || y == 10 || y == 12)
{
List<int> i = new List<int>();
for (int x = 1; x <= 31; x++)
{
i.Add(x);
}
comboBox4.DataSource = i;
}
if (y == 4 || y == 6 || y == 9 || y == 11)
{
List<int> i = new List<int>();
for (int x = 1; x <= 30; x++)
{
i.Add(x);
}
comboBox4.DataSource = i;
}
}