If you need to query for the lack of values, then use Null in your criteria
In Microsoft Access, there is a difference between querying for no value, (Null), and querying for empty strings, (exemplified as to double quotes with nothing between them: “”). Also keep in mind that a space, “ “, is not a null or empty string, but a blank character.
Query for the absence of a value
Use the NULL keyword in your criteria when you need to see all records were one of the fields has no data. If on the other hand you wish to see records were a particular field has to have any kind of data, use IS NOT NULL as your criteria.
Expecting nothing and got something?
Sometimes you may use Null as a criteria and notice a record missing that should be in your analysis. The mostly likely culprit will be a space, " ", in the field. Simply click in the field, delete the space and run your query again.
