, , VB. , Variant , , , . . VB- . , .
As. TextContent :
Dim TextContent As String
, :
Dim NumberContent As Long
. Visual Basic. String, Date, Boolean ( ), Long (, ), single ( ) Currency ( , ).
VB Access. → : Microsoft Visual Basic (Microsoft Visual Basic Help → Microsoft Visual Basic help) Visual Basic. Visual Basic for Applications Language Reference → Visual Basic Language Reference → Data Types.
, . , .
:
TextContent = " "
. .
Dim TextContent
'
TextContent = TextBoxOne.Value
'
TextBoxOne.Value = TextBoxTwo.Value
'
TextBoxTwo.Value = TextContent
, , , . . , . . .
: , ( ). . , = (), < ( ), > ( ) ( ). , Price=10 . ( Price 10) ( ). . Visual Basic .
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. . , , If. If , . , Access .
If, , Price 100. , Access :
If Price > 100 Then
MsgBox ", ."
End If
, If If End If. If , . , , .
. , , . , (Country) .
' ,
Dim TaxRate
If Country = "U.S.A." Then
' (7%)
TaxRate =1.07
Elself Country = "Canada" Then
' (14%)
TaxRate =1.14 Else
'
TaxRate =1 End If
'
TotalWithTax.Caption = Price * TaxRate
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I f . Access - , , . , End I f, , . , Access Else ( ). . 17.2 .
. 17.2. , , . (On Current), ,
. And Or , . .
15 , . : WantsEmail Email Address. WantsEmail (Yes), EmailAddress
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. WantsEmail (No), EmailAddress . VB- , If ( 1):
1 Private Sub Form_BeforeUpdate(Cancel As Integer)
' ,
2 If WantsEmail = True Then
' , EmailAddress
3 If EmailAddress = "" Or IsNull(EmailAddress) Then
' .
'
4 MsgBox "You can't be notified without an email address."
5 Cancel = True
6 End If
7 End If
8 End Sub
.
■ 1 , (On Before Update). , True () False () Cancel, .
■ 2 If, WantsEmail.
■ 3 . , , . , ( ) (. . ; . null . " " 4).
4 . , , If True. False ( WantsEmail EmailAddress ), Access .
If , . ( , ) . , , .
1 . , . .
■ 5 Cancel, (On Before Update). , .
■ 68 : If .
Access , , (On Before Update). Cancel, . , True , .
