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If you’re a beginner looking to kick-start your journey in managing and manipulating databases, SQL (Structured Query Language) is an indispensable tool that you need to get familiar with. SQL lets you handle extensive databases, make queries, retrieve data and edit the collected data to match your requirements. In this quick SQL crash course, we will lead you into the dynamics of SQL.
Understanding SQL
At a fundamental level, SQL is a language that gives you the ability to interact with databases. A DBMS (Database Management System) that uses SQL is comprised of the following components: tables, schema, views, indexes, records (or rows), and fields (or columns). SQL gives you the power to create, retrieve, update and delete these components.
Setting Up Your SQL Environment
To run SQL queries, you’ll need access to a database. If you don’t already have one set up, you can download and install a database system, like MySQL or PostgreSQL. Most of these systems come with some sample databases you can use for practice.
Your First SQL Query
Let’s dive right into it. SQL revolves around the usage of statements, and one of the fundamental types of SQL operations is the SELECT statement which you make use of whenever you want to select specific data from a database.
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-- Select all fields from a table SELECT * FROM table_name; |
This is a basic query that returns all columns from the table you specify.
Filtering Your Results With WHERE
When dealing with a large dataset, you need to filter your data to get the desired results. This is where the WHERE clause comes into play. The WHERE clause is used to filter records.
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-- Select records where age is greater than 20 SELECT * FROM table_name WHERE age > 20; |
Table Modification With SQL
For managing the data within your tables, SQL provides INSERT and DELETE statements. INSERT allows you to add data to your tables, while DELETE helps you scrap unwanted data.
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-- Insert a new record INSERT INTO table_name (column1, column2) VALUES (value1, value2); -- Delete a record DELETE FROM table_name WHERE condition; |
That’s the basics of SQL! With just these tools alone, you’re well on your way to becoming proficient in SQL. Keep practicing and exploring different commands and queries, and you will find SQL to be an immensely powerful tool in managing and manipulating databases.