通过combobox1的选择筛选combobox2的内容？
举个例子说一下，combobox1连接的是access数据库中一个表的“省份”，combobox2连接的是access数据库中同一个表的“城市”，通过选择combobox1的省份，例如：山东，combobox2下拉表的内容就只是山东的城市，我在combobox2连接的适配器的查询器里编写了select distinct 城市 from table where 省份＝ '+trim(combobox1.text)+ ',程序表示无法识别，但编写了select distinct 城市 from table where 省份＝ '山东 '就可以了，请求各位高手支招！谢谢了
[解决办法]
Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged
Dim cmd As New SqlCommand( "select distinct 城市 from table where 省份＝ '+trim(combobox1.text)+ ' ", SqlConnection1)
Dim da As New SqlDataAdapter(cmd)
SqlConnection1.Open()
Dim ds As New DataSet
da.Fill(ds)
ComboBox2.DisplayMember = "城市 "
ComboBox2.ValueMember = "城市 "
ComboBox2.DataSource = ds.Tables(0)
End Sub
