PLZ help me in working with null values in a table

[MOHAMMEDHABBOUB]

Hello everybody,

First of all, I do not know if it's the right section to post such a topic

Anyway,I need help in working with null values in a table. I have a table in which I want to create query - in "select by attribute" window- about <NULL> values, So my query is:

SELECT * from Table_name where
[Field_name] IS NULL

but no record is selected even though the table contain lots of <NULL> values (see attached image)

What could be the problem?

[AlexanderGray]

This is not really the right forum but I can answer.  Your fields are not null they have an empty string.  Empty strings and null are not the same thing from a database perspective.  If your fields were truly null they would show <Null> in the field.
try:
[Field_name] = ''  (two single quotes)