|Developer(s)||D. Richard Hipp|
|Initial release||August 2000|
|Stable release||22.214.171.124 (November 19, 2014) [±]|
SQLite (// or //) is a relational database management system contained in a C programming library. In contrast to other database management systems, SQLite is not implemented as a separate process that a client program running in another process accesses. Rather, it is part of the using program.
SQLite is a popular choice as embedded database for local/client storage in application software such as web browsers. It is arguably the most widely deployed database engine, as it is used today by several widespread browsers, operating systems, and embedded systems, among others. SQLite has bindings to many programming languages.
Unlike client–server database management systems, the SQLite engine has no standalone processes with which the application program communicates. Instead, the SQLite library is linked in and thus becomes an integral part of the application program. (In this, SQLite follows the precedent of Informix SE of c. 1984) The library can also be called dynamically. The application program uses SQLite's functionality through simple function calls, which reduce latency in database access: function calls within a single process are more efficient than inter-process communication. SQLite stores the entire database (definitions, tables, indices, and the data itself) as a single cross-platform file on a host machine. It implements this simple design by locking the entire database file during writing. SQLite read operations can be multitasked, though writes can only be performed sequentially.
D. Richard Hipp designed SQLite in the spring of 2000 while working for General Dynamics on contract with the United States Navy. Hipp was designing software used onboard guided missile destroyers, which were originally based on HP-UX with an IBM Informix database back-end. The design goals of SQLite were to allow the program to be operated without installing a database management system or requiring a database administrator. In August 2000, version 1.0 of SQLite was released, based on gdbm (GNU Database Manager). SQLite 2.0 replaced gdbm with a custom B-tree implementation, adding support for transactions. SQLite 3.0, partially funded by America Online, added internationalization, manifest typing, and other major improvements.
SQLite implements most of the SQL-92 standard for SQL but it lacks some features. For example it has partial support for triggers, and it can't write to views (however it supports INSTEAD OF triggers that provide this functionality). While it supports complex queries, it still has limited ALTER TABLE support, as it can't modify or delete columns.
SQLite uses an unusual type system for an SQL-compatible DBMS; instead of assigning a type to a column as in most SQL database systems, types are assigned to individual values; in language terms it is dynamically typed. Moreover, it is weakly typed in some of the same ways that Perl is: one can insert a string into an integer column (although SQLite will try to convert the string to an integer first, if the column's preferred type is integer). This adds flexibility to columns, especially when bound to a dynamically typed scripting language. However, the technique is not portable to other SQL products. A common criticism is that SQLite's type system lacks the data integrity mechanism provided by statically typed columns in other products. The SQLite web site describes a "strict affinity" mode, but this feature has not yet been added. However, it can be implemented with constraints like
Several computer processes or threads may access the same database concurrently. Several read accesses can be satisfied in parallel. A write access can only be satisfied if no other accesses are currently being serviced. Otherwise, the write access fails with an error code (or can automatically be retried until a configurable timeout expires). This concurrent access situation would change when dealing with temporary tables. This restriction is relaxed in version 3.7 when write-ahead logging (WAL) is turned on enabling concurrent reads and writes.
A standalone program called sqlite3 is provided that can be used to create a database, define tables within it, insert and change rows, run queries and manage an SQLite database file. This program is a single executable file on the host machine. It also serves as an example for writing applications that use the SQLite library.
SQLite has automated regression testing prior to each release. Over 2 million tests are run as part of a release's verification. Starting with the August 10, 2009 release of SQLite 3.6.17, SQLite releases have 100% branch test coverage, one of the components of code coverage. The tests and test harnesses are proprietary.
- ADO.NET adapter, initially developed by Robert Simpson, is maintained jointly with the SQLite developers since April 2010.
- ODBC driver has been developed and is maintained separately by Christian Werner. Werner's ODBC driver is the recommended connection method for accessing SQLite from OpenOffice.org.
- COM (ActiveX) wrapper making SQLite accessible on Windows to scripted languages such as JScript and VBScript. This adds database capabilities to HTML Applications (HTA).
- XULRunner uses SQLite
- The browsers Google Chrome, Opera, Safari and the Android Browser all allow for storing information in, and retrieving it from, a SQLite database within the browser, using the Web SQL Database technology, although this is rapidly becoming deprecated (namely superseded by IndexedDB).
- Mozilla Firefox and Mozilla Thunderbird store a variety of configuration data (bookmarks, cookies, contacts etc.) in internally managed SQLite databases, and even offer an add-on to manage SQLite databases.
Web application frameworks
- Bugzilla, Mozilla's bug database written in Perl can use SQLite to store data and settings.
- Django, a Python web framework, supports SQLite3 by default.
- As of version 7, Drupal, a PHP-based content management system for making websites and blogs, has an option to install using SQLite.
- Ruby on Rails' default database management system is also SQLite.
- web2py, a Python web framework, default database management system is also SQLite.
- Skype is a widely deployed application that uses SQLite.
- Adobe Systems uses SQLite as its file format in Adobe Photoshop Lightroom, a standard database in Adobe AIR, and internally within Adobe Reader.
- The Service Management Facility, used for service management within the Solaris and OpenSolaris operating systems, uses SQLite internally.
- Flame, a malware program used for cyberespionage, used SQLite to store the data it collects.
- The Xojo Programming Language has SQLite support built in to both the desktop and web frameworks.
Because of its small size, SQLite is well suited to embedded systems, and is also included in:
- Blackberry's BlackBerry 10 OS
- Microsoft's Windows Phone 8
- Apple's iOS
- Symbian OS
- Nokia's Maemo
- Google's Android
- Linux Foundation's MeeGo
- LG's webOS
- FreeBSD where starting with 10-RELEASE version it is the core package management system.
- Oracle Solaris 10 where the Service Management Facility database is serialized for booting.
However, it is also suitable for desktop operating systems; Apple adopted it as an option in OS X's Core Data API from the original implementation in Mac OS X 10.4 onwards, and also for administration of videos and songs, and storage of text messages on the iPhone.
- Comparison of relational database management systems
- List of relational database management systems
- Flat file database
- Similar database engines:
- "Recent SQLite News". 2014-11-19. http://www.sqlite.org/news.html. Retrieved 2014-11-19.
- "SQLite Copyright". sqlite.org. Retrieved May 17, 2010.
- D. Richard Hipp (presenter) (May 31, 2006). An Introduction to SQLite (video). Google Inc. Event occurs at 00:01:14. Retrieved March 23, 2010. "[...] ess-kju-ellite [...]"
- D. Richard Hipp (presenter) (May 31, 2006). An Introduction to SQLite. Google Inc. Event occurs at 00:48:15. Retrieved March 23, 2010. "[...] sequelite [...]"
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- "SQL Features That SQLite Does Not Implement". SQLite. January 1, 2009. Retrieved October 14, 2009.
- "Frequently Asked Questions". SQLite. January 26, 2009. Retrieved February 7, 2009.
- "Write Ahead Logging in SQLite 3.7". SQLite. Retrieved September 3, 2011. "WAL provides more concurrency as readers do not block writers and a writer does not block readers. Reading and writing can proceed concurrently"
- "Case-insensitive matching of Unicode characters does not work". SQLite Frequently Asked Questions. Sqlite.org. Retrieved May 11, 2011.
- "How SQLite Is Tested". SQLite. Retrieved September 12, 2009.
- ReleaseLog SQLite.org, visited 8th December 2013
- "Fossil: Fossil Performance". Fossil-scm.org. August 23, 2009. Retrieved September 12, 2009.
- DBD::SQLite: Perl DBI Interface to SQLite
- PySQLite: Python bindings for SQLite
- SQLite/Ruby: Ruby bindings for SQLite
- "sqlite — Sqlite Wrappers". SQLite. February 7, 2009. Retrieved February 7, 2009.
- "Databases". Django Documentation. Django Software Foundation. Retrieved 13 November 2012.
- "Drupal 7".
- "Skype client using SQLite?". Mail-archive.com. August 28, 2007. Retrieved June 14, 2010.
- "Well-Known Users of SQLite". Sqlite.org. Retrieved June 14, 2010.
- "Well-known Users of SQLite". Sqlite.org. Retrieved June 14, 2010.
- Allen, Grant; Owens, Mike (November 5, 2010). The Definitive Guide to SQLite (2nd ed.). Apress. p. 368. ISBN 1-4302-3225-0.
- Kreibich, Jay A. (August 17, 2010). Using SQLite (1st ed.). O'Reilly Media. p. 528. ISBN 0-596-52118-9.
- van der Lans, Rick F. (September 7, 2009). The SQL Guide to SQLite (1st ed.). lulu.com. p. 542. ISBN 0-557-07676-5.
- Newman, Chris (November 9, 2004). SQLite (Developer's Library) (1st ed.). Sams. p. 336. ISBN 0-672-32685-X.
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