MySQL

MySQL Definition

• The Primary Key constraint uniquely identifies each record in a table. Primary keys must contain UNIQUE values, and cannot contain NULL values.
• The FOREIGN KEY is a field in one table, refers to the PRIMARY KEY of another table.
• KEYs (INDEXes) are defined on certain columns to facilitate fast search on these columns. We would use SHOW INDEX FROM tableName \G to display the details on indexes.

CREATE INDEX email_index ON Users(email);

MySQL Query

• w3schools MySQL learning
• NTU Lecture
• Sample MySQL DB

MySQL Explain

• Add EXPLAIN before select statement show analyzing how queries are executed.

MySQL vs MongoDB

MySQL	Mongo DB
Schema-based	Schema-less
Relational DB	Non-relational DB
Table-structure system	Document-based system
	Does not gurantee data integrity due lack of relation