field textbox code

[balu]

dear friends,
I have an field text box on a form for which i want to write some function &
store that value in the table ( after function),for writing the code i first
set focus in desighn view ( data contrl source not changed) and written the
vb code in the code window
probably in its form module ,but nothing has functioning well
kindly help me (1) how to build code
(2) how to store the value in the field
balu

 

[balu]

dear daniel,
you have understood it perfectly
my form control source not changed ,but i wnt some thing to happen before
the data got stored in table . for eg, sum or datediff function , for which i
should write function in field text box control source ,then that field text
box exhibhit the out come of my function ,but iwant to save the same in the
same field ?
(2) how to write functions code by vb to calculate and save
kindly help me
yours balu