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L for Beginners: Mastering the Basics
Welcome to our beginner’s guide on SQL (Structured Query Language), the standard and one of the most widely used languages for managing data held in a relational database management system. SQL plays a vital role in data analysis, and understanding its basics is crucial for anyone who is considering a career in the data field. In this blog post, you will learn the basics of SQL from creating a table to performing simple queries.
## What is SQL?
SQL or Structured Query Language is a language designed to handle data in relational databases. It’s a standard language for performing database operations. SQL can help you to create, modify, update, manipulate, and retrieve data from relational databases.
The Fundamentals of SQL
Structured Query Language consists of several types of statements. The most common SQL statements:
– SELECT: Retrieves data from a database
– INSERT INTO: Adds new data into a database
– UPDATE: Modifies data in a database
– DELETE: Removes data from a database
– CREATE DATABASE: Creates a new database
– ALTER DATABASE: Modifies a database
– CREATE TABLE: Creates a new table
Creating a Table
Here is an example of the Create Table statement:
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CREATE TABLE Employees ( ID INT PRIMARY KEY, Name VARCHAR (100), Age INT, Salary DECIMAL (10, 2) ) |
This SQL statement creates a new table in the system named ‘Employees’. Each employee has a unique ID, and information about their Name, Age, and Salary.
Selecting Data
This is how you can retrieve data from the table:
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SELECT * FROM Employees |
The above command (‘SELECT * FROM Employees’) will select all data from the table ‘Employees’.
Adding Data
You can add data to your table using an INSERT INTO statement:
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INSERT INTO Employees (ID, Name, Age, Salary) VALUES (1, 'Tim', 32, 60000.00) |
This statement will insert a New Employee named ‘Tim’ who is 32 years old and his salary is 60,000.
Updating Data
To modify existing records in a table, the UPDATE statement is used:
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UPDATE Employees SET Age = 33 WHERE Name = 'Tim' |
With the above command, Tim’s age will be updated to 33 in the ‘Employees’ table.
Deleting Data
You can delete records with the DELETE statement:
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DELETE FROM Employees WHERE Name='Tim' |
With this command, the record containing the employee name ‘Tim’ will be deleted from the ‘Employees’ table.
Wrap Up
These were some of the basics of SQL you can start practicing with. Constant practice will eventually lead to mastery. Start creating your own tables, inserting values, and retrieving them to familiarize yourself with the process. In a subsequent tutorial, we will delve deeper and show you how to perform more complex queries. So, keep exploring!