For an instructor lead, in-depth look at learning SQL click below.
Welcome, budding data enthusiasts! Today, we take our first deep dive into the world of SQL, the language that allows us to communicate with databases, structure, and analyze massive amounts of data. Strap in, we’re about to start our crash course.
Section 1: What is SQL?
SQL, or Structured Query Language, is a programming language used to manage and manipulate databases. They allow us to create, retrieve, update and delete database records. Not only that, but SQL is also used to manage and control access to the database itself!
Section 2: Getting started with SQL Commands
2.1 The ‘SELECT’ Command
The ‘SELECT’ command is one of the basics in SQL. It is used to select data from a database. The data returned is stored in a ‘result table’ which we call a ResultSet. Here’s an example:
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-- fetch all records from the Employees table SELECT * FROM Employees |
2.2 The ‘WHERE’ Clause
The ‘WHERE’ clause is used to filter records. It’s only used to extract only those records that fulfill a specified condition. Here’s an example:
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-- fetch employee records where the Age is greater than 30 SELECT * FROM Employees WHERE Age>30 |
Section 3: Inserting, Updating and Deleting Data
3.1 INSERT INTO Statement
The ‘INSERT INTO’ statement is used to insert new records into a table. Here’s an example:
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-- insert a new employee record into the Employees table INSERT INTO Employees (FirstName, LastName, Age) VALUES ('John', 'Doe', 28) |
3.2 UPDATE Statement
The ‘UPDATE’ statement is used to modify the existing records in a table. Here’s an example:
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-- update Age for the employee whose FirstName is 'John' and LastName is 'Doe' UPDATE Employees SET Age = 29 WHERE FirstName = 'John' AND LastName = 'Doe' |
3.3 DELETE Statement
The ‘DELETE’ statement is used to delete existing records in a table. Here’s an example:
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-- delete the employee whose FirstName is 'John' and LastName is 'Doe' DELETE FROM Employees WHERE FirstName = 'John' AND LastName = 'Doe' |
Conclusion
Congratulations, you’ve made it to the end of this crash course on SQL basics. But remember, practice makes perfect. So, keep exploring, keep coding, and keep learning!