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Structured Query Language (SQL) is a programming language that helps you manipulate and retrieve data from databases. Used by small businesses and large corporations alike, it is a critical skill in today’s technologically driven world. This guide is intended to provide beginners with a comprehensive overview of SQL basics.
What is a Database?
In simple terms, a database is an organized collection of data. Think of it as a warehouse for information where data is stored, managed, and updated. SQL interacts with this warehouse to fetch, modify, delete, and add data.
Understanding SQL
SQL (Structured Query Language) is the standard language for dealing with Relational Databases. SQL can be used to insert, search, update, and delete database records. That doesn’t mean SQL cannot do things beyond that. In fact, SQL can do lots of functions including optimizing and maintenance of databases.
Getting Started: Basic SQL Commands
The most basic commands in SQL include “SELECT”, “UPDATE”, “DELETE”, “INSERT INTO”, and “WHERE”.
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-- SELECT statement is used to fetch the data from a database. SELECT * FROM Customers; |
This command would get all the data from the ‘Customers’ table.
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-- INSERT INTO statement is used to insert a new row in a database. INSERT INTO Customers (CustomerID, CustomerName) VALUES ('CST001', 'John Doe'); |
This command would create a new entry in the ‘Customers’ table with the ID ‘CST001’ and name ‘John Doe’.
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-- UPDATE statement is used to modify the existing records in a database. UPDATE Customers SET CustomerName='Jane Doe' WHERE CustomerID = 'CST001'; |
This command would change the name of the customer with the ID ‘CST001’ to ‘Jane Doe’.
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-- DELETE statement is used to delete existing records from a database. DELETE FROM Customers WHERE CustomerID = 'CST001'; |
This command would remove the customer with the ID ‘CST001’ from the ‘Customers’ table.
Now that you know the basics of SQL, you can delve deeper into this language and discover its wide range of capabilities! Remember, practice is key in mastering SQL, so try out these codes and experiment with your own combination of commands.