Skip to content

Database

Notes are from a course on Zero to Mastery I am currently doing-->

Database⚑

It's a structured set of data which is structured in a certain way so that it can be scaled as and when required.

SQL⚑

SQL is a query language for navigating through a database. SQL is used to create, read, modify and delete records from a database.

Query⚑

A query, in SQL, is a way to make database engines understand user's instructions.

Example: SELECT * FROM Users WHERE role='manager

breakdown of above example:

  • SELECT: literal meaning.
  • *: identifier (can be any column name from a table). * means select all available fields
  • FROM: literal meaning
  • Users: Name of the table
  • WHERE: literal meaning
  • role='manager: expression. role is a column name. this essentially means, return record only is column role matches the value manager

Comments⚑

In SQL, a line prefixed with == will be treated as a comment, and won't be executed.

SQL is a Declarative Language.

TODO: Learn more about declarative and imperative language.

Original name of SQL is SEQUEL.

SELECT Statement⚑

Used to print/get data from a database.