Sum database column for an ATM simulation

[variouz3ckz]

we are required to do a simple atm machine-like, using vb6... that able user to deposit, withdraw and check balance...
my problem is... i cannot sum up the amount the user wants to deposit and the balance the user has in the database(im using MS ACCESS)

should i use number as its data type?!

plz help me guys...

im expecting your helpsss ASAP... tnx

[hariharanmca]

we are .............

Ofcourse set Data type to number and at the bottom (General) FieldSize to Double then use a query like

[CODE=vb]Dim strSql As string
strSql = "Select sum(amountField ) As TotalAmount from tblTableName where userID = " & intUserId [/CODE]

[variouz3ckz]

Ofcourse set Data type to number and at the bottom (General) FieldSize to Double then use a query like

[CODE=vb]Dim strSql As string
strSql = "Select sum(amountField ) As TotalAmount from tblTableName where userID = " & intUserId [/CODE]

ei i used this code, in the deposit but when i check the balance it end to error indicating that invalid use of null...

this is my code for DEPOSIT

Private Sub Command1_Click( )
With Data1.Recordset


.Edit
str1 = balance + Val(txt_balance )
!balance = txt_balance
.Update

MsgBox "TRANSACTIO N SUCCESSFUL"

txt_deposit = ""
txt_deposit.Set Focus



End With
End Sub

and this is my code for check balance

Private Sub cmd_check_Click ()
With Data1.Recordset

lbl_balance = !balance



End With

End Sub