SQL SELECT Tutorial

The SELECT statement in SQL is used to retrieve data from a database. It is one of the most commonly used commands in SQL and is essential for querying and analyzing data.

Basic Syntax

The basic syntax of the SELECT statement is as follows:

SELECT column1, column2, ...
FROM table_name;

• column1, column2, …: The columns you want to retrieve.
• table_name: The name of the table from which you want to retrieve data.

Example

Let’s say you have a table named Employees with the following columns: EmployeeID, FirstName, LastName, and Salary.

To retrieve all columns from the Employees table, you would use:

SELECT * FROM Employees;

To retrieve only the FirstName and LastName columns, you would use:

SELECT FirstName, LastName FROM Employees;

Filtering Data with WHERE Clause

You can filter the data using the WHERE clause. For example, to retrieve employees with a salary greater than 50000:

SELECT FirstName, LastName, Salary
FROM Employees
WHERE Salary > 50000;

Sorting Data with ORDER BY

You can sort the results using the ORDER BY clause. For example, to sort employees by salary in descending order:

SELECT FirstName, LastName, Salary
FROM Employees
ORDER BY Salary DESC;

Limiting Results with LIMIT

To limit the number of rows returned, you can use the LIMIT clause. For example, to retrieve the top 5 highest-paid employees:

SELECT FirstName, LastName, Salary
FROM Employees
ORDER BY Salary DESC
LIMIT 5;

Conclusion

The SELECT statement is a powerful tool for querying data in SQL. By mastering its various clauses, you can efficiently retrieve and analyze data from your database.

For more advanced queries, consider learning about JOINs, GROUP BY, and HAVING clauses.