null problems

[retreiver]

hi, I am a little stumped on whats going on with my access form. basically i have a quantity coloum where the user would enter the quantitys manually
The quantity is then multipled to the amount coloum and that value is put into the total value coloum.im running queries using vba wich sorts the $50 and $200, so i know how many 50 $ there are out of the total and 200 $. it alll worked fine... till i had to make a button so the user could clear the quantity fields in the table. now im getting a null error.

if someone could please look at the attached file and figure out where im going wrong it would be greatly appreciated thanks

 

[jmcilhinney]

If your column is supposed to represent a quantity then allowing null isn't really logical. You should make the field required and "clearing" it should mean setting it to zero. Zero should also be its default value.

 

[romabr]

i was check it in txb_TextChanged() function for this field .
if txb.text="" then txb.text="0"