Form Search - Based upon multiple combo boxes
A note about the queries used in this db

    In order to retain their simplified SQL, which is easier to understand, the following queries should not be opened in query design grid view.
    (a) Q_Books
    (b) Q_LookUpAuthor_A
    (c) Q_LookUpYear_A

    (If any of these queries gets opened in design grid view, Access will convert the SQL into bloated state that would be difficult to follow / understand)

 

    Back-up copies of these queries have been included with the prefix "ZZZ_", so that if you do happen to land into design grid view of the original query, leading to its distortion (though OK from performance point of view), you can restore the original state, by copying from the ZZZ_ version of that query.

 

    For adding further combo boxes in the search criteria, sample building block to be included in continuation of  Where clause is:

 

And ((FieldName Like [Forms]![F_Search]![CboName]) Or (Trim([Forms]![F_Search]![CboName])= "ALL"))

 

    Simultaneously, the following sample component will get added to PARAMETERS clause, just before the semicolon:

 

, [Forms]![F_Search]![CboName] Text ( 255 )

    Note - In the Lookup Lists for combo boxes, " ALL" has a leading space so as to ensure that this option is at top of the list. (Select it in full, including the leading space, when manually replacing by a direct entry)