Update All Records Displayed From Form Using 1 Textbox

Hi there,

I have a form which displays data from a combo box in the header of my form.

Each row of the detail from the form contains two values from the database.. one is called case ref and the other is a checkbox for completed.

Here is what I want to do....

1) chose which rows I want to update by selecting the checkbox (I can do this)
2) I have put another text box in the header with a button.. this box captures the case ref (I have done this bit too)
3) When the button is clicked, I want to loop through all the records displayed on the form and update those with the checkbox ticked to the value of the text box header.... now I can update one row, but how do I update all of them????

Help would be much appreciated

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