Data structure
First thing you need to do is to set up a database. What does it mean to "set up a database" anyway? It's putting data into table(s) and joining them via relations. Let's have a look on the raw data I copied from the Fantastic Fiction website:
Series Hercule Poirot 1. The Mysterious Affair at Styles (1920) 2. The Murder on the Links (1923) 3. Poirot Investigates (1924) 4. The Murder of Roger Ackroyd (1926) 5. The Big Four (1927) 6. The Mystery of the Blue Train (1928) 7. Peril at End House (1932) 8. Lord Edgware Dies (1933) aka Thirteen at Dinner (...) 19. Hercule Poirot's Christmas (1938) aka A Holiday for Murder / Murder for Christmas (...) Miss Marple 1. The Murder at the Vicarage (1930) 2. The Thirteen Problems (1932) aka The Tuesday Club Murders 3. The Body in the Library (1942) (...)
So, there are two protagonists, monsieur Hercule Poirot and Miss Marple, and some novels have alternative titles. You could then compile the data into one table like this:
title|aka|protagonist|year The Mysterious Affair at Styles||Hercules Poirot|1920 The Murder on the Links||Hercules Poirot|1923 Poirot Investigates||Hercules Poirot|1924 The Murder of Roger Ackroyd||Hercules Poirot|1926 The Big Four||Hercules Poirot|1927 The Mystery of the Blue Train||Hercules Poirot|1928 The Murder at the Vicarage||Miss Marple|1930 Peril at End House||Hercules Poirot|1932 The Thirteen Problems|The Tuesday Club Murders|Miss Marple|1932 Lord Edgware Dies|Thirteen at Dinner|Hercules Poirot|1933 Hercule Poirot's Christmas|A Holiday for Murder|Hercules Poirot|1938 The Body in the Library||Miss Marple|1942
However, there are two problems here:
- redundant data ("Hercules Poirot" and "Miss Marple" are present several times)
- no way to insert Hercule Poirot's Christmas second alternative title (Murder for Christmas)
Redundant data is bad: not only it occupies space, but it may also become incoherent (eg. because of typos). Furthermore, in case a change is needed, you would have to change all instances.–Lack of data is even worse. There must be a way to insert this second alternative title!