SQL (Structured Query Language) Introduction

SQL (Structured Query Language) Introduction


2 min read

In order to become familiar with SQL and SQL-based platforms, one have to gain basic knowledge about some of the basic concepts. Here I will list what seems to be to be important to know before jumping to learn any SQL-based platform. These concepts helps you to have a big picture about what you are about to learn and why you need to use them. Of course, I might change this list over the time as I myself gain more and more experienced in teaching SQL. For some the following concepts I have written a small description and for others I don't; anyway, this is to provide a checklist for your start point, not to provide you with extensive definitions. I'm sure you can find many comprehensive definitions using search engines and generative AI tools.

Important basic have-to-knows before learning SQL:

  1. What are Database?

  2. What is a Relational Database?

  3. What is SQL (Structured Query Language)?

  4. What are the most popular SQL-Based Databases?

    • MySQL:Fast and scalable, Commercial Open Source.

    • Oracle: Commercial, Enterprise-Scale.

    • MariaDB: Open Source.

    • PostgreSQL: Opensource.

    • Some other smaller projects like: SQLite, HSQL, ...

  5. What does CRUD (Create, Read/Select, Update, Delete) mean?

    The four basic actions that one can do using databases are:

    • Creating/Inserting Data

    • Read/Select some Data

    • Update Data

    • Delete Data

  6. In a Relational Database, what does a Database represent?

    It contains one or more tables.

  7. In a Relational Database, what does a Relation/Tuple represent?

    It contains tuples and attributes.

  8. In a Relational Database, what does a Tuple/Row represent?

    a set of fields which generally represent an "Object", like a person or a music track

  9. In a Relational Database, what does an Attribute/Column/Field represent?

    One pf the possible many elements of data corresponding to the object represented by the row

    Image from https://en.wikipedia.org/wiki/Relational_database

  10. What is a Database Schema?

  11. What is the SQL Architecture? How SQL commands are run on a SQL Server (regardless of what kind of SQL Client and/or Server you are using)?

    Picture from "Database Design and Basic SQL in PostgreSQL" coursera course>Week1>"SQL Architeture"