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0501 | Introduction to SQL and Databases

Disclaimer | Attribution​

This short "SQL 101" is based on my own notes taken during the Google Cybersecurity video course by Google.

Databases​

  • using databases allow us to store large amounts of data while keeping it quick and easy to access

Database​

  • an organized collection of information or data
  • can be accessed by multiple people simultaneously
  • can store massive amounts of data
  • perform complex tasks while accessing data

Spreadsheets​

  • often designed for a single user or a small team to store less data

Relational database​

  • a structured database containing tables that are related to each other
  • each table contains fields of information
  • these are the columns of the tables
  • example 
    -----------------
    employees (table)
    -----------------
    employee_id (field)
    device_id (field)
    username (field)
    department (field)
    office (field)
    -----------------
  • rows are called records
  • rows are filled with specific data related to the columns in the table
  • often multiple tables
  • connecting two tables is possible | if they share a common column | they are called keys

Primary key​

  • a column where every row has a unique entry
  • must not have any duplicate values, or any null or empty values
  • allows for unique identification of the rows in the table
  • a table can have only one primary key

Foreign key​

  • a column in a table that is a primary key in another table
  • can have empty values and duplicates
  • allows for two tables to connect together
  • a table can have multiple foreing keys

Query databases with SQL​

SQL | Structured Query Language​

  • a programming language used to create, interact with, and request information from a database

Query​

  • a request for data from a database table or a combination of tables

Log​

  • a record of events that occur within an organization's systems

Accessing SQL from Linux​

  • from the linux cli | sqlite3