SQL is “structured” in the sense that it follows a very specific set of rules. A computer program can parse a formulated SQL query easily. In fact, the O’Reilly book lex & yacc by John Levine, Tony Mason, and Doug Brown implements an SQL grammar to demonstrate the process of writing a program to interpret language! A query is a fully specified command sent to the database server, which then performs the requested action. Here’s an example of an SQL query:
SELECT name FROM people WHERE name LIKE 'Stac%'
As you can see, this statement reads almost like a form of broken English: “Select names from a list of people where the names are like Stac.” SQL uses few of the formatting and special characters that are typically associated with computer languages.