For an instructor lead, in-depth look at learning SQL click below.
Welcome to this SQL Crash Course. No matter if you’re a businessman, developer, analyst, or anyone who deals with large amounts of data, SQL is a great tool worth understanding. Let’s dive into a beginner’s roadmap to learning SQL with actual SQL code examples.
What is SQL?
SQL, Structured Query Language, is a programming language primarily used for managing and manipulating data in relational databases. SQL operations include storing, retrieving, and manipulating data stored in a relational database.
Basic SQL Syntax
1. SELECT statement:
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-- Selects all columns from a table SELECT * FROM Employees |
2. WHERE clause:
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-- Selects columns from a table where a certain condition is met SELECT * FROM Employees WHERE salary > 50000 |
3. COUNT function:
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-- Provides the total number of rows in a table SELECT COUNT(*) FROM Employees |
Digging Deeper: Intermediate SQL Syntax
1. Join Operation:
This is used to combine rows from two or more tables based on a related column between them.
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-- Joining two tables on a common column SELECT Orders.OrderID, Customers.CustomerName FROM Orders INNER JOIN Customers ON Orders.CustomerID = Customers.CustomerID; |
2. Group By Statement:
The GROUP BY statement groups rows that have the same values in specified columns into aggregated data, like the sum, average, or count.
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-- Grouping data based on certain columns and calculating total salary SELECT department, COUNT(id), SUM(salary) FROM Employees GROUP BY department; |
3. Creating a Database:
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-- Creates a new database CREATE DATABASE myDatabase; |
Conclusion
This post painted a broad overview of SQL, from understanding what SQL is, to some basic and intermediate SQL syntax. There’s still so much more to learn including complex queries, database normalization, stored procedures and much more. However, with the foundational knowledge provided in this article, you’re well on your way to becoming proficient in SQL. Keep practicing and never stop learning!