Database Normalization: Keys, Forms, and Integrity Rules
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Database Keys and Normal Forms
You guarantee uniqueness by designating a Primary Key (PK) - a column or set of columns that contains unique values for a table.
Foreign Key (FK) is a column in one table that references the primary key of another table.
Database Normal Forms
First Normal Form (1NF)
It states that all column values must be atomic.
Second Normal Form (2NF)
A table is in 2NF if it is in 1NF and every non-key column is fully dependent on the entire PK. That is, tables should store data relating to only one “thing” (or entity), and that entity should be fully described by its primary key.
Third Normal Form (3NF)
A table is in 3NF if it is in 2NF and if all non-key columns are mutually independent.