Intro to Database Systems - Part 1 : A quick intro to db

Let’s start with some new vocabulary and acronyms:

As data models, we can have :

relationalDB.png

The main advantages of the relational model are :

Some advantages of more complex data models like the pre-relational model (network/hierarchy) or the post-relational (OO/XML) are the fact that they have :

The advantage of the Key-value model is its simplicity, but it’s also the main drawback.

An Entity-Relationship Model is a diagram describing the requirements of the database. It contains:

A transaction is a single logical operation on the data (read/write). The ACID model, defining 4 properties, guarantees that a database transaction is processed reliably:

 
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Intro to Database Systems - Part 11 to 13 : Integrity Constraints

Constraints are there to impose restrictions on what data is allowed in the database. The basic E/R model introduces us to 2 types of constraints: KEYS Multiplicities The relational model allows us to be more flexible. It imposes bounds... Continue →