Expression Criteria for Access -

i've created database 15000 records , want create form filters records according entries inputed in textboxes through query. of columns i've used expression :

like "*" & [forms]![testform]![testtxt] & "*" 

i use "like" if user decides not input in textbox, query ignores parameter. when comes dates (i have 2 columns contain dates) can't make ignore empty textbox when user decides not write anything. can me make expression below show records in query if datetesttxt empty ?

> [forms]![testform]![datetesttxt] 

if you're using query designer, add condition

is null 

so visually in query builder like:

criteria: > [forms]![testform]![datetesttxt]       or: null 

update:

this should work single expression:

is null or > [forms]![testform]![datetesttxt] 

and more correct solution in case if have conditions on more 1 column