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Introduction to SQL

Learn how and why we use SQL to interact with databases.

Structured Query Language (SQL) is the most widely implemented database query language and is supported by many popular relational database systems, including: MS SQL Server, IBM DB2, MySQL, and Microsoft Access. It is primarily used to access data from relational databases.

Since the late 1980s, SQL (pronounced ‘S Q L’ or ‘sequel’) has been a standard for both the International Organization for Standardization (ISO) and the American National Standards Institute (ANSI). Although SQL is considered a standard, database technology providers usually have their own SQL editor and there can be small variations in the syntax depending on how the SQL features are implemented.

In this course you’ll use SQLite3, which implements a database engine and understands most of the standard SQL language. We’ll try to highlight general SQL statements and any specific SQLite implementations. You can also check out the following pages for more information:

SQLite3 [1]
SQL as understood by SQLite [2]
Quirks, caveats, and gotchas in SQLite [3]

To help you learn SQL, we’ll present snippets of SQL. You’ll generally see examples of SQL presented like this:

CREATE TABLE Customers (
 CustomerID integer PRIMARY KEY AUTOINCREMENT,
 LastName varchar(255),
 FirstName varchar(255),
 DOB varchar(255),
 Mobile integer,
 CountryCode char(4) 
);

We’ll also show the output of any SQL or SQLite commands as follows

sqlite> SELECT * FROM Artist;
ArtistId Name 
---------- ----------
1 AC/DC 
2 Accept 
3 Aerosmith 
...

References

_{1. What is SQLite? [Internet]. SQLite. Available from: https://sqlite.org/index.html}
_{2. SQL As Understood By SQLite [Internet]. SQLite. Available from: https://sqlite.org/lang.html}
_{3. Quirks, Caveats, and Gotchas In SQLite [Internet]. SQLite. Available from: https://sqlite.org/quirks.html}