Question 19 (continued from previous response):

DELETE FROM Employee
WHERE department = 'Finance';

SELECT department, COUNT(ID) AS TotalEmployees
FROM Employee
GROUP BY department;

UPDATE Employee
SET salary = salary * 1.10
WHERE department = 'HR';

' General Declarations Section (at the top of the form's code module)
Option Explicit

Dim FirstNumber As Double
Dim SecondNumber As Double
Dim Operator As String
Dim IsNewNumber As Boolean ' Flag to indicate if a new number is being entered

Private Sub Form_Load()
    ' Initialize on form load
    txtDisplay.Text = "0"
    IsNewNumber = True
End Sub

' --- Digit Buttons (0-9) ---
Private Sub btn0_Click()
    Call AddDigit("0")
End Sub

Private Sub btn1_Click()
    Call AddDigit("1")
End Sub

Private Sub btn2_Click()
    Call AddDigit("2")
End Sub

Private Sub btn3_Click()
    Call AddDigit("3")
End Sub

Private Sub btn4_Click()
    Call AddDigit("4")
End Sub

Private Sub btn5_Click()
    Call AddDigit("5")
End Sub

Private Sub btn6_Click()
    Call AddDigit("6")
End Sub

Private Sub btn7_Click()
    Call AddDigit("7")
End Sub

Private Sub btn8_Click()
    Call AddDigit("8")
End Sub

Private Sub btn9_Click()
    Call AddDigit("9")
End Sub

' Helper function to add digits to the display
Private Sub AddDigit(Digit As String)
    If IsNewNumber Then
        txtDisplay.Text = Digit
        IsNewNumber = False
    Else
        If txtDisplay.Text = "0" And Digit = "0" Then
            ' Do nothing if trying to add 0 to 0
        ElseIf txtDisplay.Text = "0" And Digit <> "0" Then
            txtDisplay.Text = Digit ' Replace initial 0 with the new digit
        Else
            txtDisplay.Text = txtDisplay.Text & Digit
        End If
    End If
End Sub

' --- Decimal Button ---
Private Sub btnDecimal_Click()
    If InStr(txtDisplay.Text, ".") = 0 Then ' Only add if no decimal exists
        txtDisplay.Text = txtDisplay.Text & "."
    End If
    IsNewNumber = False
End Sub

' --- Operator Buttons ---
Private Sub btnPlus_Click()
    Call SetOperator("+")
End Sub

Private Sub btnMinus_Click()
    Call SetOperator("-")
End Sub

Private Sub btnMultiply_Click()
    Call SetOperator("*")
End Sub

Private Sub btnDivide_Click()
    Call SetOperator("/")
End Sub

' Helper function to set the operator
Private Sub SetOperator(Op As String)
    If Not IsNewNumber Then ' If an operation is pending or a number was just entered
        If FirstNumber = 0 Then ' First number not yet set
            FirstNumber = CDbl(txtDisplay.Text)
        Else ' An operation was already performed or an operator was pressed consecutively
            ' Perform previous calculation if an operator was already set
            If Operator <> "" Then
                Call CalculateResult
            End If
            FirstNumber = CDbl(txtDisplay.Text) ' Store current display as first number
        End If
    End If
    Operator = Op
    IsNewNumber = True ' Next digit entry will start a new number
End Sub

' --- Equals Button ---
Private Sub btnEquals_Click()
    Call CalculateResult
    Operator = "" ' Clear operator after calculation
    IsNewNumber = True ' Next digit entry will start a new number
End Sub

' Helper function to perform the calculation
Private Sub CalculateResult()
    If Operator = "" Then Exit Sub ' No operator set

    SecondNumber = CDbl(txtDisplay.Text)
    Dim Result As Double

    Select Case Operator
        Case "+"
            Result = FirstNumber + SecondNumber
        Case "-"
            Result = FirstNumber - SecondNumber
        Case "*"
            Result = FirstNumber * SecondNumber
        Case "/"
            If SecondNumber = 0 Then
                MsgBox "Cannot divide by zero!", vbCritical
                Result = 0
            Else
                Result = FirstNumber / SecondNumber
            End If
    End Select

    txtDisplay.Text = CStr(Result)
    FirstNumber = Result ' Store result as the new first number for chained operations
End Sub

' --- Clear Button ---
Private Sub btnClear_Click()
    txtDisplay.Text = "0"
    FirstNumber = 0
    SecondNumber = 0
    Operator = ""
    IsNewNumber = True
End Sub