How can I learn SQL all over again if I were to start over? During your early days of learning you find yourself always in a dilemma of where to start learning SQL, What resources best suites your learning journey, What is the correct way to learn SQL and it seems like you are in a state of confusion, right?

This is a comprehensive guide for beginners trying to set foot in the data industry. SQL(Structured Query Language) is a programming language used for manipulating relational databases

1. Define database(s)

• Define what a database is and the list out different types of databases(i.e relational and non relational databases)
• Install and set up a database management system on your local machine

2. Basics of SQL

• Define SQL and state features of SQL
• What are the common Data Types mostly used in SQL
• Understand basic syntax of SQL queries

3. Basic Commands in SQL

• Select statement It is used to retrieve data from tables e.g

select name, age
from students

• Sorting and filtering data Using order by to sort data, where to filter data based on a condition and limit clause to specify number of to be returned by a query
• Aggregate functions Learn to use MAX, MIN, AVERAGE, COUNT, SUM

• Group by and Having Clause
  group data and understand how to filter grouped data

  4. Data manipulation

• Insert
  add new records to a table

• update
  Modify existing records in a table

• delete
  remove records from a table in a database

  5. Database design

• relationships
  understand how tables are related via primary and foreign keys, and the different types of relationships(i.e one to one, one to many)

• Database normalisation
  Define normalisation and the different types of normalisation

  6. Advaced SQL Queries

• Subqueries
  Writing a query inside another query

• Joins
  Combining one or more rows of data from multiple tables using joins i.e(inner join, left join, right join, cross join)

• Indexing
  Define indexing and the importance of indexes

  7. SQL functions and procedures

• Functions
  What are functions and the inbuilt SQL functions

• Triggers and procedures
  Define procedures and triggers, types of triggers and their applications

  8. Practice writing SQL

• Hands on practice
  Login to chatgpt and ask chatgpt to produce dummy data to insert to your database
  Lastly, ask chatgpt to formulate questions to practice writing your SQL queries

• Join an online community
  Join whatsapp, Linked in and SQL groups on social media.

Conclusion

By following this road map as beginner, you will build your skills in SQL. Ensure you have lots of practice so as to be proficient in SQL.