Database systems

Notes  http://www.ime.usp.br/~jef/notes.pdf

SQL http://www.atlasindia.com/sql.htm

Normalization

Normalization

Normalization of a database helps in modifying the design at later times and helps in being prepared if a change is required in the database design.

http://www.atlasindia.com/sql.htm

1nd Normal Form or 1NF:

Each Column Type is Unique.

2nd Normal Form or 2NF:

1NF +  all attributes within the entity should depend solely on the entity’s unique identifier.

3rd Normal Form or 3NF:

2NF +  no column entry should be dependent on any other entry (value) other than the key for the table.  If such an entity exists, move it outside into a new table.

 

A slightly detailed article (PDF) covers Lossless Join etc.

References

1.  Introduction to Normalization 

2. Problems without normalization – namely insertion anamoly, update anamoly and deletion anamoly

3. Functional dependency , Armstrongs axioms and Normalization

4. http://www.slideshare.net/jitendratomar/dbms7

5. https://www.youtube.com/watch?v=IwswNIZ_PSg

6. DBMS stores data internally in form of btrees

B-Trees are used to store the data on external storage like disks. Unlike main memory, disk access are expensive. So B-Trees tries to minimize the access

http://www.bluerwhite.org/btree/
http://jorendorff.github.io/hackday/2012/library/

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