Help with Arrays and References

Hi,

   I'm starting on PostgreSQL so please be patient; =]

   I'm building a book library database in which I have a table
TBL_FORMAT which keeps basic information on various file-formats (ie 1,
PDF, Portable Document Format) and a TBL_BOOKS which I want to reference
TBL_FORMAT. But the column Format inside TBL_BOOKS is an array, as a
book may exist in one or more file types. My doubt is: If I make
something like

   CREATE TABLE "tbl_books" (
   "id_book" int4 DEFAULT nextval('TBL_Books_ID_Books_Seq'::text) NOT NULL,
   "format" _int4 NOT NULL REFERENCES TBL_Format ON_UPDATE CASCADE,
   ...

   will the CASCADE action update my TBL_Books (Format) keeping the
other values in the array or will it erase all and set the new Format value?

   Thanks,

William

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