90 days roadmap to learn SQL

Anand Thati

1 year ago

Structured Query Language or SQL is a standard database language used to maintain, update, and store data in several relational databases like MySQL, Oracle, SQL Server, and PostgreSQL. Whether you want to become a web developer or a data scientist, learning and practicing SQL is one of the essential skills.

As a software engineer, you will work with several applications and programs, but they all have fundamental requirements for writing and reading data. If you have been lenient with your SQL skills so far, this 90-day roadmap will provide a systematic plan to learn SQL for solving real-time problems and crack the interviews.

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First 30 days

Start with the basic concepts of SQL. The first 30 days of your learning should be dedicated to learning the basics of SQL query writing. There are some essential concepts that you should know first before you start working with big data sets.

Here are the topics that you will focus on for the first month.

Creating a database. This is the obvious first step toward learning SQL. Here is an excellent tutorial on how to create a database in SQL. Then you must move on to learn how to create tables and agitator to the data tables using the INSERT command.

Next, you should learn the following commands:

SELECT Clause: It is used to retrieve or fetch data from the database.
FROM Clause: It is a selection clause that defines which database to select data from.
WHERE Clause: WHERE is the conditional query on which data is retrieved.
DELETE Statement: It is used for deletion tasks.
AND and OR operators: They act like the And and Or operators in any other programming language.
Drop and Truncate: These commands are used to drop or truncate the dataset per the condition.
NOT Operator: To select the data that is not based on the given condition.

Day 31 to Day 60:

After the first month, you need to step forward and dive into more advanced SQL concepts. In SQL, it is possible to run advanced queries on a large volume of data. While the basic queries that you will learn in the first month of the roadmap are enough to work with a small database for optimized and practical use applications, you will need to focus on the following clauses.

WITH Clause: It is a clause that allows you to create sub-query blocks within the SQL.
Arithmetic operators: Common arithmetic operators make data filtering very convenient and precise, but they have a learning curve in SQL.
FETCH Clause: FETCH is another necessary clause that you can use to filter a large amount of data based on conditions.
Wildcard operators: Arguably, one of the most important features of SQL queries is wildcards that allow you to select exact data intelligently.
UPDATE and ALTER statements: These are the clauses we use to manipulate the data within a database based on certain conditions.
LIKE clause: To search data based on a pattern given on the condition.
BETWEEN and IN operator: To select the data range between or in the given conditions in the database.
CASE statement: It is similar to the IF-ELSE conditional statements in the programming language and looks for data as per the respective case.
EXISTS: It creates a nested query to filter out the data that exists in another query.

Once you are done with these advanced concepts of SQL, you will be able to work with larger applications that produce or handle huge volumes of data.

Day 61 to Day 90:

Join in SQL is another important concept that you must know to be able to practically use SQL. A Join clause combines rows from two or more tables in SQL based on a related column between them.

Here are the essential Join clauses that you must know.

Union clause: It functions the same as a mathematical Union operator and results in the union of the given tables.
Aliases: It will create an alias of the table that we can refer to later.
Intersection clause: Intersection is used to join two or more tables at the point of intersection.
Inner, Left, Right, and Full Joins: When we have to join one table with another, these are the most common types of joins we use.
Cartesian join and Self join: These are the common joins that we used to query some data from an SQL table based on conditions.

Conclusion

Learning these concepts alone will not be enough; you must practice what you know. You should take on a practice SQL project to guide your learning. Apart from this, here are some additional resources to learn SQL:

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