Access Form Multiple Checkbox's auto-populate the 3rd based off the 1st and 2nd Checkbox RRS feed

  • Question

  • I have 3 Checkboxes on my form and I'm trying to make the third checkbox automatically populate if the first 2 are checked, see below...Any suggestions on how this can be completed? For the Third checkbox Field C1, I need it to auto-populate with True or Yes or -1 based off the 1st 2 being checked and if one of the 1st 2 is not then leave it blank...

    IIf([A1]="Yes" And [B1]="Yes",[C1]=-1,"")

    • Edited by Mac1206 Tuesday, February 18, 2020 1:28 PM
    Tuesday, February 18, 2020 12:43 PM

All replies

  • Set the Control Source of the third check box to

    =[A1] And [B1]

    Regards, Hans Vogelaar (

    Tuesday, February 18, 2020 2:23 PM
  • You could try entering the following in the [C1] fields Control Source:

    =IIf([A1]=True And [B1]=True,True,False)

    Checkboxes can't be "blank". They are either True (-1) or False (0).

    Tuesday, February 18, 2020 3:46 PM

  • Checkboxes can't be "blank". They are either True (-1) or False (0).

    That's true of a Boolean column, but not of a check box control.  In fact, even a check box control bound to a Boolean column with no default value is Null until data is inserted into any bound control in a form.

    To implement Codd's 3-way logic, for instance, a column of short integer data type would be used, allowing values of -1 or 0, and also allowing Null (Required property = False in Access).  In addition to Boolean TRUE or FALSE values a bound check box control can then represent a NULL, for which the control is greyed out.

    In the present context Hans's solution using a Boolean AND operation is by far the most elegant.

    Ken Sheridan, Stafford, England

    Tuesday, February 18, 2020 6:53 PM