Normal Forms: 1NF, 2NF, 3NF and BCNF
A relation that stores two independent facts in one row repeats one of them, and repetition causes anomalies.
Database Management Systems · topic
Normal forms and decomposition
1NF, 2NF, 3NF and BCNF with their exact conditions and the anomalies they remove, a routine for the highest normal form, lossless-join tests (common attributes and the chase), dependency preservation, 3NF synthesis and BCNF decomposition; 4NF as a marked note.
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Lossless-Join and Dependency-Preserving Decomposition
, R_n whose attributes together cover R. Splitting is only safe if two properties hold. The decomposition must be lossless: joining the pieces back must give exactly the original relation, with no extra (spurious) tuples.
Normal forms and decomposition cheat sheets
One-page visual sheets for this topic, in the sheet library on the store. Previews are free; the full sheets come with the subject pack.