What is structured query language?

Structured Query Language (SQL) is a computer language for relational database management and data manipulation.

Examples:

SELECT FirstName, LastName, City FROM Customer

SELECT 'Total income is', ((OrderQty * UnitPrice) * (1.0 - UnitPriceDiscount)), ' for ',
p.Name AS ProductName
FROM Production.Product AS p
INNER JOIN Sales.SalesOrderDetail AS sod
ON p.ProductID = sod.ProductID
ORDER BY ProductName ASC;