One of the most common questions when getting started with database programming is “How Do I Learn SQL Basics?” The good news is that there are not too many things that you need to know. And it’s very easy to learn SQL.
Whenever you get started, you need to begin by understanding the core concepts of what databases are and how they work. You should understand the essential Structured Query Language (SQL or “sequel”) commands that we use to interact with the database. And you should be familiar with the different types of database platforms that are most commonly used.
Basic SQL Database Concepts
There are a handful of essential concepts that you should understand about databases. Any book, course, or tutorial that you take should cover these topics in a reasonable amount of depth.
Most commonly, we store data in a Relational Database. This means that we can create relationships between different types of data within the database. We often house our databases in a software product or platform called a Relational Database Management System (RDBMS). We interact with an RDBMS through the use of the Structured Query Language (SQL). This gives us a common language for communicating with our relational database.
In a relational database, we store data in structures called tables. A table is a collection of columns and rows. If you’re familiar with Microsoft Excel spreadsheets, you can think of a workbook as a sort of table. Down the left side, you have rows. Across the top you have columns.
Each table should represent a specific type of data. It is always helpful to associate a table with a physical entity. For example, you might store information about a customer in a table called “customers”. You might store information about a product in a table called “products”. But you wouldn’t store information about a product in the “customers” table because those are two different things.
Understanding how to design your table structure and create tables in a database is a fundamental concept. Any course material that you choose should cover this topic in great depth and give you hands-on exercises to practice creating tables.
Database Columns and Data Types
As we mentioned before, a database table is a collection of columns and rows. When you create a table in SQL, you have to define the specific columns in that table. A column is essentially a small piece of data that gets stored in a table. You might have a column named “customer_name” in your customers table. It might also contain a column called “customer_phone_number”.
As you define the columns, you have to give each one a name. You also have to specify a data type for each column. Data types define what kind of data you can store in a column. You might store text, which is just a combination of letters, numbers, spaces, and other characters. Or you might store numeric data or dates in various formats.
Understanding the data types that SQL uses is important because you cannot create a database without specifying data types. When you’re researching how to go about learning SQL, you should make sure that your introduction to SQL course provides a detailed overview of columns and data types.
Primary and Foreign Keys
Once of the most important things to learn about SQL databases is how to create relationships between tables. This is done using special columns in each table. Each table should have a primary key, which is one or more columns that are used to uniquely identify each row.
When you specify a relationship between two tables, you will use columns in one table to point to a primary key in another table. This is called a foreign key relationship. For example, let’s say you have a customer with an ID of 1. You want to associate a project to that customer. So you might add a “customer_id” field to your “projects” table. Then you can put the value “1” in that “customer_id” field and now your project will be associated to customer ID 1.
As you learn SQL basics, you should make sure that you understand primary keys and foreign keys thoroughly. These are critical concepts and you will encounter them with virtually any database that you interact with. If you don’t understand these, then it may lead to creating databases where the data is not stored reliably.
Essential SQL Commands
We interact with SQL databases using commands (often referred to as queries). There are a handful of SQL commands that you will need to learn in order to master database development. Fortunately, you can do 85% or more of your SQL coding work using just a few key commands.
- SELECT statements allow you to extract data from a table
- INNER JOIN, LEFT JOIN, RIGHT JOIN and other JOIN statements allow you connect two or more tables together for more powerful SQL queries
- WHERE clauses allow you to filter data based on specific criteria
- GROUP BY statements allow you to aggregate data, for example to add up values from all rows in a numeric column
- ORDER BY clauses allow you to sort data, for example alphabetically
- INSERT statements allow you to put data into a table
- UPDATE statements allow you to change data in a table
- DELETE statements allow you to take data out of a table permanently
These are the most common SQL statements that you will use. They are also very powerful commands that can be combined to do really cool and useful things.
Any SQL database coding course that you take should cover these commands at the very least. Once you’re done with the course, you should be comfortable writing SQL queries using any of these statements.
Learn SQL Basics the Easy Way
The best way to learn SQL is the way that works best for you personally. You should research the different options that are available to you and make a plan for how you will approach it. But, you must make sure that any course you take will help you learn SQL basics that are outlined here. These are the most essential things that you’ll need to know in order to be successful in your career.
Always review the table of contents, course content listing, or syllabus for any materials that you’re going to buy or use. If you do this, then you will find that learning SQL is easy and actually very fun!