how to build table relationships in a firebird database? I am a beginner in Delphi and I have a Firebird database with 2 tables namely masterlist and daily collection. I used Zeos 7.0.3 to access my Firebird database.

My masterlist contains the following columns:

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║ name ║ date ║ balance ║ status ║
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My daily collection contains the following columns:

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║ date ║ name ║ payment ║ balance ║
╚══════╩══════╩═════════╩═════════╝


I would like to build a relation in which the balance from masterlist will be copied to the balance column of the daily collection, and when I update the column in the daily collection it will also update the content of the masterlist.

Hope this will be considered a good question I have tried very hard to make a useful question.
While I'm pretty sure you should redesign your database at first (and probably read something on SQL basics), you can get what you want with triggers :)

This one inserts row into daily collection with appropriate balance:

CREATE trigger masterlist_ai for masterlist
active after insert position 0
AS
begin
  insert into "daily collection" (  "date",     balance)
                        values (new."date", new.balance);
end


And this one updates balance in masterlist after updates of daily collection (assuming date is the primary key):  

CREATE trigger "daily_collection_au" for "daily collection"
active after update position 0
AS
begin
  update masterlist
  set balance = new.balance
  where "date" = new."date";
end