How to Learn SQL in 2023
In 2023, SQL (Structured Query Language) remains one of the most popular programming languages used in the field of databases and data analytics. Learning SQL can be useful both for those who are just starting their journey in IT, and for experienced professionals who want to expand their knowledge and skills. In this article, we’ll look at a few tips and resources to help you learn SQL in 2023 and stay on top of the latest trends and developments in the field.
According to the website Indeed.com, in 2023, the requirements for candidates in jobs related to databases and data analysis include knowledge of SQL as a required skill. Some of these popular jobs include SQL Developer, Data Analyst, Database Administrator, Business Intelligence Analyst, and more. According to Glassdoor, SQL-skilled professionals can earn between $50,000 and $100,000 per year, depending on region and level of experience. In this regard, learning SQL can be useful for those who want to improve their chances in the labor market and earn high wages in the IT field.
Roadmap for learning SQL in 2 months
Why did I make a roadmap for exactly 2 months? Naturally, this will not cover all the skills for those who want to learn SQL, but it will help to fully understand the basic concepts of SQL, how to work with it and what it is for. After going through this path in 2 months, you will be able to continue your SQL training in the future and turn your immediately made “ship of knowledge” into a real Japanese “knowledge battleship Yamato” to improve your skill.
Here is a roadmap for learning SQL in 2 months:
Week 1: SQL Basics
Learning basic SQL concepts such as tables, columns, rows and data types
Creating simple SELECT queries to retrieve data from a table
Learn to filter data with WHERE and LIKE clauses
Week 2: Advanced SELECT queries
Explore aggregate functions such as COUNT, SUM, AVG, and MAX/MIN
Learning GROUP BY and HAVING to group and filter data
Learning JOIN statements to combine data from multiple tables
Week 3: Creating and modifying tables
Learning the CREATE TABLE command to create new tables
Learning the ALTER TABLE command to change the structure of a table
Learning the DROP TABLE command to drop a table
Week 4: Change and delete data
Learning the INSERT command to add new rows to a table
Learning the UPDATE Command to Change Existing Rows
Learning the DELETE Command to Delete Rows from a Table
Week 5: Database Basics
Learning database concepts such as primary and foreign keys
Learning the CREATE DATABASE command to create a new database
Learning the USE command to select a database to work with
Week 6: Working with indexes and limits
Exploring indexes to speed up data lookups in a table
Examining Data Protection and Table Integrity Constraints
Week 7: Working with views and stored procedures
Explore views to create virtual tables based on queries
Learning stored procedures to create custom functions and processes
Week 8: Consolidation of the studied material
Repetition and deepening of knowledge through practical tasks and projects
Preparing for certification exams, if needed
By following this roadmap, you will be able to learn SQL walkthrough in 2 months and gain enough knowledge to work with databases and analyze data. However, do not forget that practice is the key to success, so do not forget to regularly complete practical assignments and projects to consolidate the learned material.
The theoretical minimum of databases
Learning SQL without theory is an extremely strange thing, you need to know what the whole foundation stands on. I will describe the basic concepts of databases:
To work with databases, you need to understand the following concepts and terms:
The relational data model is a model for representing and organizing data in a database. In the relational model, data is stored in tables of rows and columns. Each table has a name and a structure defined by a set of columns and their data types.
A table is the main object in the relational data model that stores data in rows and columns. Each table has a unique name and structure defined by a set of columns and their data types. In a table, each row represents a record, and each column represents a particular property or attribute of an object.
A column is a single field in a table that stores data of the same type. Each column has a unique name and data type, which determines what type of data can be stored in the column.
A row is one entry in a table that contains data for each column. Each row in a table has a unique identifier called a key. The key can be composite, i.e. may include multiple columns.
The key is a unique identifier for each entry in the table. The key can be composite, i.e. may include multiple columns that together provide uniqueness for a record in a table. The key is used to link data in different tables and to provide quick access to data.
A foreign key is a relationship between two tables that is used to link the data in those tables. A foreign key is a column in one table that refers to a key in another table. This allows you to link data in different tables and create relationships between them.
An index is a data structure that allows you to quickly find data in a table. An index is created on one or more columns in a table and stores links to the corresponding records in the table. Using indexes can significantly speed up the execution of queries against a table.
A query is a command to retrieve data from a table or tables in a database. Queries can include selection, sorting, filtering, and grouping operations. The result of a query is a set of data that can be used for further processing or display to the user.
SQL is a structured query language that is used to work with relational databases. SQL allows you to perform operations to create, modify and delete tables and data in them, as well as to retrieve data from tables using queries. SQL is the standard for dealing with relational databases and is used by most DBMSs.
Where and how to learn SQL for free?
SQLZoo(https://sqlzoo.net/) is a free resource that provides interactive lessons and tasks for learning SQL. Lessons start with simple queries and build up in difficulty as you progress.
W3Schools SQL (https://www.w3schools.com/sql/) is a popular site for learning SQL and other programming languages. Contains many lessons and examples with the possibility of practical application.
Codecademy SQL (https://www.codecademy.com/learn/learn-sql) – an interactive course for learning SQL with the possibility of practical application in practice.
SQLbolt(https://sqlbolt.com/) is a free resource that provides lessons and tasks for beginners and advanced SQL users.
Khan Academy SQLhttps://www.khanacademy.org/computing/computer-programming/sql) is a free SQL course that provides lessons and tasks for learning the language.
(Udacity SQL)https://www.udacity.com/course/sql-for-data-analysis–ud198) is a SQL course from Udacity that will teach you the basics of the SQL language and its application in data analysis.
Learn SQL (https://learnsql.com/) is a paid resource for learning SQL. Contains a large number of lessons and practical tasks.
SQLCourse(http://www.sqlcourse.com/) is a free resource for learning SQL. Contains lessons, assignments and tests to test knowledge.
SQL Tutorial (https://www.sql-tutorial.ru/) is a free resource for learning SQL in Russian. Contains lessons and assignments for practical application.
Mode Analytics SQL Tutorial (https://mode.com/sql-tutorial/) is a free SQL course from Mode Analytics that will teach you basic and advanced SQL skills.
SQL Exercises (https://www.sql-ex.ru/) is a free resource with tasks and exercises for learning SQL. Contains tasks for practical application in practice.
SQL Fiddle(http://sqlfiddle.com/) is a free online SQL editor that allows you to create, test and debug SQL queries.
Learn SQL the Hard Way (https://learncodethehardway.org/sql/) is a book for learning SQL, containing lessons and tasks for practical work.
SQL Zoo (https://www.sqlzoo.net/wiki/AdventureWorks) is a free SQL learning resource containing lessons and activities based on the AdventureWorks database.
DataCamp SQL (https://www.datacamp.com/courses/intro-to-sql-for-data-science) – SQL course from DataCamp, which will teach you the basics of the SQL language and its application in data analysis. Contains lessons and practical tasks in practice.
Good books for learning SQL
Here are some good books in Russian for learning SQL:
SQL for Dummies by Alan Bewley is a popular book for beginners that provides readers with the basics of SQL and practical examples.
“SQL – Database Query Language” by A. A. Stepanov is a book containing the basics of SQL and SQL query examples.
“SQL. The Complete Guide” by Alexander Kuznetsov is a book that offers a comprehensive guide to SQL, including language basics, queries, database design, and performance optimization.
“SQL. A collection of recipes. 2nd ed.” Author: Robert de Graaf, Anthony Molinaro – Ready-made recipes for solving practical problems when working with Oracle, DB2, SQL Server, MySQL and PostgreSQL DBMS are considered.
Where to go next?
“If you are not moving forward, then you are moving backward. Never stop there.” – Tom Clancy
If you think that you have exhausted your knowledge in SQL, I suggest you start working on these skills:
Some of the hardest skills in SQL include:
Query Optimization – This requires knowledge of the structure of tables and indexes, as well as an understanding of how to optimize queries to improve performance.
Working with large amounts of data – this may include managing partitioning, clustering, and other methods for processing and analyzing large amounts of data.
Use of analytic functions – this may include the use of functions such as RANK, ROW_NUMBER, LAG, and LEAD to execute complex analytic queries.
Working with time series data – this may include using time series functions such as the DATE_TRUNC, DATE_PART and WINDOW functions to analyze and manipulate time series data.
Working with Geographic Data – This may include using special functions such as ST_Distance, ST_Within, and ST_Intersection to parse and manipulate geographic data.
Working with data warehouses – this may include using ETL (Extract, Transform, Load) functions to extract, transform and load data into data warehouses.
Working with Procedures and Triggers – This may involve creating and managing procedures and triggers to automate tasks and ensure data integrity.
Working with Relational Algebra – This may involve using various operators such as JOIN, UNION, INTERSECT and EXCEPT to perform complex queries.
Working with indexes – this may include creating and managing indexes to improve query performance.
Dealing with data security – this may include managing access to data and protecting data from unauthorized access.
In conclusion, learning SQL in 2023 is a key skill for anyone who works with data. SQL is one of the most widely used relational database languages today, and the demand for professionals with SQL skills is still high.