Public Class Form9
    Dim conn As New ADODB.Connection
    Dim rs As New ADODB.Recordset
    Dim rss As New ADODB.Recordset
    Dim str As String
    Dim sql As String
    Private Sub Form9_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        conn = OpenConn()

        sql = "select 药品编号 from 药品信息"
        ComboBox2.Items.Clear()
        rs.Open(sql, conn)
        Do While Not rs.EOF
            str = Trim(rs(0).Value)
            ComboBox2.Items.Add(str)
            rs.MoveNext()
        Loop
        rs.Close()
        sql = "select 病人编号 from 病人信息 "
        ComboBox1.Items.Clear()
        rs.Open(sql, conn)
        Do While Not rs.EOF
            str = Trim(rs(0).Value)
            ComboBox1.Items.Add(str)
            rs.MoveNext()
        Loop
        rs.Close()
    End Sub


    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        If Trim(ComboBox1.SelectedItem) = "" Then
            MsgBox("请选择病人！")
            Exit Sub
        End If
        If Trim(ComboBox2.SelectedItem) = "" Then
            MsgBox("请选择药品！")
            Exit Sub
        End If
        sql = "insert into 配药单 values('" & Trim(ComboBox1.SelectedItem) & "','" & Trim(ComboBox2.SelectedItem) & "',GETDATE(),'" & Trim(TextBox2.Text) & "')"
        rs.Open(sql, conn)

        sql = "update 病人信息 set 总费用 = 总费用 + " & Int(Trim(TextBox2.Text)) * Int(Trim(TextBox1.Text)) & " where 病人编号 = '" & Trim(ComboBox1.SelectedItem) & "'"
        rs.Open(sql, conn)

        MsgBox("添加成功")


        Me.Close()
        CloseConn(conn)

    End Sub

    Private Sub TextBox1_TextChanged(sender As System.Object, e As System.EventArgs) Handles TextBox1.TextChanged
    End Sub

    Private Sub TextBox2_TextChanged(sender As System.Object, e As System.EventArgs) Handles TextBox2.TextChanged
        If (TextBox2.Text <> "") Then
            Label5.Text = "总价格为" & Int(Trim(TextBox2.Text)) * Int(Trim(TextBox1.Text)) & "元"
        End If

    End Sub

    Private Sub Button4_Click(sender As System.Object, e As System.EventArgs) Handles Button4.Click
        Me.Close()
    End Sub

    Private Sub ComboBox2_SelectedIndexChanged(sender As System.Object, e As System.EventArgs) Handles ComboBox2.SelectedIndexChanged
        sql = "select 价格 from 药品信息 where 药品编号 = '" & Trim(ComboBox2.SelectedItem) & "'"
        rs.Open(sql, conn)
        TextBox1.Text = Trim(rs(0).Value)
        rs.Close()
    End Sub

    Private Sub Label4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)

    End Sub
End Class
     

打错了，
是vs运行结果