Checkbox Yes/No Change on Dropbox Change

I have a Combo Box (cbo1) that list available Items. When I select an item in cbo1, I would like it change a checkbox to True (or Yes).

cbo1 gets data from tblLOG where Box (checkbox) is NO Query

I've tried using

UPDATE tblLOG 
Set Box = True
WHERE Serial = cboSerial

Actual Code.

Private Sub cbo1_Change()
    Dim strSQL As String
    Dim i As Integer
    Dim Msg As String
    Dim Assm As String

    Assm = cbo1.Value

    'Exit this sub if the combo box is cleared
    Msg = "Make Update" & vbCr & vbCr

    i = MsgBox(Msg, vbQuestion + vbYesNo, "UPDATE VALUE?")
    If i = vbYes Then
        strSQL = "UPDATE tblLOG " _
        & "SET Box= True " _
        & "WHERE Serial = Assm;"
        CurrentDb.Execute strSQL, dbFailOnError
        Response = acDataErrAdded
    End If
End Sub

My Results are

Run-time error '3061': Too few parameters. Expected 1.

Solution

The reason for your error is because you are not evaluating your VBA variable Assm, but rather concatenating the string "Assm" to your SQL query.

strSQL = "UPDATE tblLOG " _
& "SET Box= True " _
& "WHERE Serial = Assm;"

If you were to Debug.Print the variable strSQL to the console, you would see the string:

"UPDATE tblLOG SET Box= True WHERE Serial = Assm;"

However, since Assm is not a string in the SQL query (i.e. it is not surrounded by single or double quotes), it is interpreted as a parameter whose value hasn't been supplied when the SQL query is subsequently executed.

To solve this, you could concatenate the evaluated value of the Assm variable, e.g.:

strSQL = "UPDATE tblLOG " _
& "SET Box= True " _
& "WHERE Serial = '" & Assm & "';"

This assumes that Serial is a text field - if this is not the case, remove the single quotes from the above.

Your entire code could be condensed somewhat to:

Private Sub cbo1_Change()
    If MsgBox("Make Update", vbQuestion + vbYesNo, "UPDATE VALUE?") = vbYes Then
        CurrentDb.Execute "update tbllog set box = true where serial = '" & cbo1 & "';", dbFailOnError
        Response = acDataErrAdded
    End If
End Sub

Though, this is still open to SQL injection, and so a better practice is to parameterise the query, e.g.:

With CurrentDb.CreateQueryDef("", "update tbllog t set t.box = true where t.serial = myserial;")
    .Parameters!myserial = cbo1
    .Execute
End With