09/19/23: For the latest on this subject see: FIRST NORMAL FORM - A DEFINITIVE GUIDE

Note: This is a 11/23/17 revision of Part 2 of a three-part series that replaced all of my previous posts on the subject (pages of which redirect here), in order to further tighten integration with the McGoveran formalization and interpretation [1] of Codd's true RDM.
(Cont'd from Part 1)
 
Part 1 raised the issue of poor understanding of Codd's concept of a simple domain with atomic values underlying 1NF. In Part 2 I clarify Codd's definition of 1NF and its correct interpretation.

Q: I am trying to remove duplicate rows from a database containing 4446 tables and when finished, merge data from that database to an existing database with the same structure. Is there an easy way to remove duplicate rows from all those 4446 tables?

A1: Please tell us "what is a 4446 table?" And, please give examples of duplicate records.

A2: Recreate your database with unique primary keys. 2) Copy records from original database to recreated database, one table at a time. The duplicate records will drop on the floor. 3) Fix the thousands of bugs in your application code that created the duplicate rows in the first place.

A3: I'm creating temporary tables + I add unique index to that table and insert data into and then I rename it to the original one.

--stackoverflow.com

[With] a declarative language and you have no real control over the execution plan. Heck, Oracle 12c can use multiple different execution plans for the same query depending on bind parameters, statistics not matching reality, and the phase of the moon.

No declarative language will ever be a first-class programming citizen in my eyes. Too much magic. Too non-linear. Too hard to debug for those reasons. They are great for when you have to do really simple things but once you step off the well worn path, you are in the thicket.
--reddit.com

09/19/23: For the latest on this subject see: FIRST NORMAL FORM - A DEFINITIVE GUIDE

Note: This is a 11/23/17 revision of Part 1 of a three-part series that replaced all of my previous posts on the subject (pages of which redirect here), in order to further tighten integration with the McGoveran formalization and interpretation [1] of Codd's true RDM.

On the one hand:

"... there is no generally accepted definition of 1NF ... the word that you see most often is 'atomic'. It is common to say that a relation is in 1NF if all its attributes [sic] are atomic ... Does 1NF equate to “atomic attribute [values]”? ... what [do] people have in mind [when they claim] atomicity? ... the [meaning] behind definitions is that you should rarely need to extract information from a value of an attribute ... But that explains why one cannot decide, depending on theory only, whether a relation is in 1NF ... it is a habitual use of data that makes attributes atomic, not theory. No wonder, there is so much mess in theory about what 1NF should be."