为什么选完comboBox1后，改选别的CHR值后comboBox2没出来值？我这样做是下拉框联动吗

private void button1_Click(object sender, EventArgs e)
{
string dbPath = @"D:\历年高考分数.db";
string sq = @"Data Source=" + dbPath;
m = new SQLiteConnection(sq);
m.Open();
SQLiteDataAdapter mAdapter = new SQLiteDataAdapter("select para1,para2,para3 from 下拉框", m);
DataSet ds = new DataSet();
mAdapter.Fill(ds);
DataTable dt = ds.Tables[0];

        ![图片说明](https://img-ask.csdn.net/upload/201907/10/1562768984_4575.png)

comboBox1.DataSource = dt;
comboBox1.ValueMember = "para1";
m.Close();
}
private void InitCityByProvince()
{
//comboBox2.Items.Clear();
string dbPath = @"D:\历年高考分数.db";
string sq = @"Data Source=" + dbPath;
m = new SQLiteConnection(sq);
m.Open();
SQLiteDataAdapter mAdapter = new SQLiteDataAdapter("select para1,para2,para3 from 下拉框", m);
DataSet ds = new DataSet();
mAdapter.Fill(ds);
DataTable dt = ds.Tables[0];
comboBox2.DataSource = dt;
comboBox2.ValueMember = "para2";
m.Close();
}

       protected void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
       {
       InitCityByProvince();
       }

DataTable dt = ds.Tables[0];
在这里调试下，看看dt里面有没有值。
另一个问题是，InitCityByProvince这个函数里并没有根据comboBox1的选择来加载数据的逻辑。换言之，comboBox1选什么，加载的数据没有区别。
是不是你的sql里忘记写where了