Editing Open Database Connectivity (section)

==History==

===Before ODBC===
The introduction of the [[Mainframe computer|mainframe]]-based [[relational database]] during the 1970s led to a proliferation of data access methods. Generally these systems operated together with a simple command processor that allowed users to type in English-like commands, and receive output. The best-known examples are [[SQL]] from [[IBM]] and [[QUEL query languages|QUEL]] from the [[Ingres (database)|Ingres]] project. These systems may or may not allow other applications to access the data directly, and those that did use a wide variety of methodologies. The introduction of [[SQL]] aimed to solve the problem of ''language'' standardization, although substantial differences in implementation remained.

Since the SQL language had only rudimentary programming features, users often wanted to use SQL within a program written in another language, say [[Fortran]] or [[C (programming language)|C]]. This led to the concept of [[Embedded SQL]], which allowed [[PostQUEL|SQL]] code to be ''embedded'' within another language. For instance, a SQL statement like <code>SELECT * FROM city</code> could be inserted as text within C source code, and during [[compiler|compiling]] it would be converted into a custom format that directly called a function within a [[Library (computing)|library]] that would pass the statement into the SQL system. Results returned from the statements would be interpreted back into C data formats like <code>char *</code> using similar library code.

There were several problems with the Embedded SQL approach. Like the different varieties of SQL, the Embedded SQLs that used them varied widely, not only from platform to platform, but even across languages on one platform – a system that allowed calls into [[IBM Db2]] would look very different from one that called into their own [[IBM SQL/DS|SQL/DS]].{{Dubious|Before-ODBC section|reason=different, how?|date=February 2013}} Another key problem to the Embedded SQL concept was that the SQL code could only be changed in the program's source code, so that even small changes to the query required considerable programmer effort to modify. The SQL market referred to this as ''static SQL'', versus ''dynamic SQL'' which could be changed at any time, like the [[command-line interface]]s that shipped with almost all SQL systems, or a programming interface that left the SQL as plain text until it was called. Dynamic SQL systems became a major focus for SQL vendors during the 1980s.

Older mainframe databases, and the newer [[microcomputer]] based systems that were based on them, generally did not have a SQL-like command processor between the user and the database engine. Instead, the data was accessed directly by the program – a programming library in the case of large mainframe systems, or a [[command line interface]] or interactive forms system in the case of [[dBASE]] and similar applications. Data from dBASE could not generally be accessed directly by other programs running on the machine. Those programs may be given a way to access this data, often through libraries, but it would not work with any other database engine, or even different databases in the same engine. In effect, all such systems were static, which presented considerable problems.

===Early efforts===
By the mid-1980s the rapid improvement in microcomputers, and especially the introduction of the [[graphical user interface]] and data-rich [[application program]]s like [[Lotus 1-2-3]] led to an increasing interest in using personal computers as the client-side platform of choice in [[client–server model|client–server]] computing. Under this model, large mainframes and [[minicomputer]]s would be used primarily to serve up data over [[local area network]]s to microcomputers that would interpret, display and manipulate that data. For this model to work, a data access standard was a requirement – in the mainframe field it was highly likely that all of the computers in a shop were from one vendor and clients were [[computer terminal]]s talking directly to them, but in the micro field there was no such standardization and any client might access any server using any networking system.

By the late 1980s there were several efforts underway to provide an abstraction layer for this purpose. Some of these were mainframe related, designed to allow programs running on those machines to translate between the variety of SQL's and provide a single common interface which could then be called by other mainframe or microcomputer programs. These solutions included IBM's Distributed Relational Database Architecture ([[DRDA]]) and [[Apple Computer]]'s [[Data Access Language]]. Much more common, however, were systems that ran entirely on microcomputers, including a complete [[protocol stack]] that included any required networking or file translation support.

One of the early examples of such a system was  [[Lotus Development]]'s [[Lotus DataLens|DataLens]], initially known as Blueprint. Blueprint, developed for 1-2-3, supported a variety of data sources, including SQL/DS, DB2, [[FOCUS]] and a variety of similar mainframe systems, as well as microcomputer systems like [[dBase]] and the early Microsoft/Ashton-Tate efforts that would eventually develop into [[Microsoft SQL Server]].<ref>McGlinn, Evan (1988), [https://books.google.com/books?id=6D4EAAAAMBAJ Blueprint Lets 1-2-3 Access Outside Data"], ''InfoWorld'', vol. 10, no. 14, 4 April 1988, pp. 1, 69</ref> Unlike the later ODBC, Blueprint was a purely code-based system, lacking anything approximating a command language like SQL. Instead, programmers used [[data structure]]s to store the query information, constructing a query by linking many of these structures together. Lotus referred to these compound structures as ''query trees''.{{sfn|Geiger|1995|p=65}}

Around the same time, an industry team including members from [[Sybase]] (Tom Haggin), [[Tandem Computers]] ([[Jim Gray (computer scientist)|Jim Gray]] & Rao Yendluri) and Microsoft (Kyle Geiger) were working on a standardized dynamic SQL concept. Much of the system was based on Sybase's DB-Library system, with the Sybase-specific sections removed and several additions to support other platforms.{{sfn|Geiger|1995|p=86-87}} DB-Library was aided by an industry-wide move from library systems that were tightly linked to a specific language, to library systems that were provided by the [[operating system]] and required the languages on that platform to conform to its standards. This meant that a single library could be used with (potentially) any programming language on a given platform.

The first draft of the ''Microsoft Data Access API'' was published in April 1989, about the same time as Lotus' announcement of Blueprint.{{sfn|Geiger|1995|p=56}} In spite of Blueprint's great lead – it was running when MSDA was still a paper project – Lotus eventually joined the MSDA efforts as it became clear that SQL would become the de facto database standard.{{sfn|Geiger|1995|p=65}} After considerable industry input, in the summer of 1989 the standard became ''SQL Connectivity'' (''SQLC'').{{sfn|Geiger|1995|p=106}}

===SAG and CLI===
In 1988 several vendors, mostly from the [[Unix]] and database communities, formed the [[SQL Access Group]] (SAG) in an effort to produce a single basic standard for the SQL language. At the first meeting there was considerable debate over whether or not the effort should work solely on the SQL language itself, or attempt a wider standardization which included a dynamic SQL language-embedding system as well, what they called a [[Call Level Interface]] (CLI).{{sfn|Geiger|1995|p=165}} While attending the meeting with an early draft of what was then still known as MS Data Access, Kyle Geiger of Microsoft invited Jeff Balboni and Larry Barnes of [[Digital Equipment Corporation]] (DEC) to join the SQLC meetings as well. SQLC was a potential solution to the call for the CLI, which was being led by DEC.

The new SQLC "gang of four", MS, Tandem, DEC and Sybase, brought an updated version of SQLC to the next SAG meeting in June 1990.{{sfn|Geiger|1995|p=186-187}} The SAG responded by opening the standard effort to any competing design, but of the many proposals, only [[Oracle Corp]] had a system that presented serious competition. In the end, SQLC won the votes and became the draft standard, but only after large portions of the API were removed – the standards document was trimmed from 120 pages to 50 during this time. It was also during this period that the name Call Level Interface was formally adopted.{{sfn|Geiger|1995|p=186-187}}  In 1995 SQL/CLI became part of the international SQL standard, ISO/IEC 9075-3.<ref name="ISO/IEC 9075-3">ISO/IEC 9075-3 – Information technology – Database languages – SQL – Part 3: Call-Level Interface (SQL/CLI)</ref> The SAG itself was taken over by the [[X/Open]] group in 1996, and, over time, became part of [[The Open Group]]'s [[Common Application Environment]].

MS continued working with the original SQLC standard, retaining many of the advanced features that were removed from the CLI version. These included features like [[Cursor (databases)#Scrollable cursors|scrollable cursors]], and [[metadata]] information queries. The commands in the API were split into groups; the Core group was identical to the CLI, the Level 1 extensions were commands that would be easy to implement in drivers, while Level 2 commands contained the more advanced features like cursors. A proposed standard was released in December 1991, and industry input was gathered and worked into the system through 1992, resulting in yet another name change to ''ODBC''.{{sfn|Geiger|1995|p=203}}

===JET and ODBC===
During this time, Microsoft was in the midst of developing their [[Jet Database Engine|Jet database system]]. Jet combined three primary subsystems; an [[ISAM]]-based database engine (also named ''Jet'', confusingly), a C-based interface allowing applications to access that data, and a selection of driver [[Dynamic-Link Libraries|dynamic-link libraries]] (DLL) that allowed the same C interface to redirect input and output to other ISAM-based databases, like [[Paradox (database)|Paradox]] and [[xBase]]. Jet allowed using one set of calls to access common microcomputer databases in a fashion similar to Blueprint, by then renamed DataLens. However, Jet did not use SQL; like DataLens, the interface was in C and consisted of [[data structure]]s and function calls.

The SAG standardization efforts presented an opportunity for Microsoft to adapt their Jet system to the new CLI standard. This would not only make Windows a premier platform for CLI development, but also allow users to use SQL to access both Jet and other databases as well. What was missing was the SQL parser that could convert those calls from their text form into the C-interface used in Jet. To solve this, MS partnered with [[PageAhead Software]] to use their existing query processor, SIMBA. SIMBA was used as a parser above Jet's C library, turning Jet into an SQL database. And because Jet could forward those C-based calls to other databases, this also allowed SIMBA to query other systems. Microsoft included drivers for Excel to turn its spreadsheet documents into SQL-accessible database tables.<ref name=simba>{{cite book |last=Harindranath |first=G |author2=Jože Zupančič |title=New perspectives on information systems development: theory, methods, and practice |url=https://books.google.com/books?id=O8Loa-c0TyoC |access-date=2010-07-28 |year=2001 |publisher=Springer |isbn=978-0-306-47251-0 |page=451 |quote=The first ODBC drivers […] used the SIMBA query processor, which translated calls into the Microsoft Jet ISAM calls, and dispatched the calls to the appropriate ISAM driver to access the backend […] }}</ref>

===Release and continued development===
ODBC 1.0 was released in September 1992.<ref>{{cite web |url=http://www.easysoft.com/developer/interfaces/odbc/linux.html#what_is_odbc |title=Linux/UNIX ODBC – What is ODBC?}}</ref> At the time, there was little direct support for SQL databases (versus ISAM), and early drivers were noted for poor performance. Some of this was unavoidable due to the path that the calls took through the Jet-based stack; ODBC calls to SQL databases were first converted from [[Simba Technologies]]'s SQL dialect to Jet's internal C-based format, then passed to a driver for conversion back into SQL calls for the database. [[Digital Equipment]] and [[Oracle Corporation|Oracle]] both contracted [[Simba Technologies]] to develop drivers for their databases as well.<ref>[http://www.simba.com/simba-history.htm "Our History"], Simba Technologies</ref>

Circa 1993, OpenLink Software shipped one of the first independently developed third-party ODBC drivers, for the [[Progress DBMS|PROGRESS DBMS]],<ref>{{cite web |last=Idehen |first=Kingsley Uyi |title=ODBC and progress V7.2d |url=https://groups.google.com/d/msg/comp.databases/ZDdiftnvkj4/AK0K2M0a0WoJ |work=Usenet Newsgroup comp.databases |access-date=13 December 2013 |date=October 1994 }}</ref> and soon followed with their UDBC (a cross-platform API equivalent of ODBC and the SAG/CLI) SDK and associated drivers for [[Progress Software|PROGRESS]], Sybase, Oracle, and other DBMS, for use on Unix-like OS ([[AIX]], [[HP-UX]], [[Solaris (operating system)|Solaris]], [[Linux]], etc.), [[OpenVMS|VMS]], [[Windows NT]], [[OS/2]], and other OS.<ref>{{cite web |last=Idehen |first=Kingsley Uyi |title=Need ODBC/Ingres driver for DEC OSF/1 |url=https://groups.google.com/d/msg/comp.databases.oracle/HSHhNjjBgf4/47PGF35h93AJ |work=Usenet Newsgroup comp.databases.oracle |access-date=13 December 2013 |date=1995-07-18 }}</ref>

Meanwhile, the CLI standard effort dragged on, and it was not until March 1995 that the definitive version was finalized. By then, Microsoft had already granted [[Visigenic Software]] a [[source code]] license to develop ODBC on non-Windows platforms. Visigenic ported ODBC to the [[classic Mac OS]], and a wide variety of Unix platforms, where ODBC quickly became the de facto standard.<ref>Sippl, Roger (1996) [http://www.drdobbs.com/sql-access-groups-call-level-interface/184410032 "SQL Access Group's Call-Level Interface"], Dr. Dobbs, 1 February 1996</ref> "Real" CLI is rare today. The two systems remain similar, and many applications can be ported from ODBC to CLI with few or no changes.<ref>[http://publib.boulder.ibm.com/infocenter/iisclzos/v9r5/index.jsp?topic=/com.ibm.swg.im.iis.fed.classic.clientsref.doc/topics/iiyfcodbcclisimdiff.html "Similarities and differences between ODBC and CLI"], InfoSphere Classic documentation, IBM, 26 September 2008</ref>

Over time, database vendors took over the driver interfaces and provided direct links to their products. Skipping the intermediate conversions to and from Jet or similar wrappers often resulted in higher performance. However, by then Microsoft had changed focus to their [[OLE DB]]<ref>{{Cite web|url=http://hal2020.com/2011/09/25/ole-db-and-sql-server-history-end-game-and-some-microsoft-dirt/|title = OLE DB and SQL Server: History, End-Game, and some Microsoft "dirt"|date = 25 September 2011}}</ref> concept (recently reinstated <ref>{{cite web |url=https://blogs.msdn.microsoft.com/sqlnativeclient/2017/10/06/announcing-the-new-release-of-ole-db-driver-for-sql-server/ |title=Announcing the new release of OLE DB Driver for SQL Server |date=6 October 2017 }}</ref>), which provided direct access to a wider variety of data sources from [[address book]]s to text files. Several new systems followed which further turned their attention from ODBC, including [[ActiveX Data Objects]] (ADO) and [[ADO.net]], which interacted more or less with ODBC over their lifetimes.

As Microsoft turned its attention away from working directly on ODBC, the Unix field was increasingly embracing it. This was propelled by two changes within the market, the introduction of [[graphical user interface]]s (GUIs) like [[GNOME]] that provided a need to access these sources in non-text form, and the emergence of [[open software]] database systems like [[PostgreSQL]] and [[MySQL]], initially under Unix. The later adoption of ODBC by Apple for using the standard Unix-side [[iODBC]] package [[Mac OS X 10.2]] (Jaguar)<ref>{{cite web |last=Anderson |first=Andrew |title=Open Database Connectivity in Jaguar |url=http://oreilly.com/pub/a/mac/2003/06/20/odbc.html |work=O'Reilly MacDevCenter.com |publisher=O'Reilly Media, Inc. |access-date=13 December 2013 |date=2003-06-20}}</ref> (which OpenLink Software had been independently providing for Mac OS X 10.0 and even Mac OS 9 since 2001<ref>{{cite web|last=Sellers |first=Dennis |title=ODBC SDK update out for Mac OS Classic, Mac OS X |url=http://www.macworld.com/article/1018465/odbc.html |work=MacWorld |publisher=IDG Consumer & SMB |access-date=13 December 2013 |date=2001-07-17 }}</ref>) further cemented ODBC as the standard for cross-platform data access.

[[Sun Microsystems]] used the ODBC system as the basis for their own open standard, [[Java Database Connectivity]] (JDBC). In most ways, JDBC can be considered a version of ODBC for the programming language [[Java (programming language)|Java]] instead of [[C (programming language)|C]]. JDBC-to-ODBC ''bridges'' allow Java-based programs to access data sources through ODBC drivers on platforms lacking a native JDBC driver, although these are now relatively rare. Inversely, ODBC-to-JDBC bridges allow C-based programs to access data sources through JDBC drivers on platforms or from databases lacking suitable ODBC drivers.

===ODBC today===
ODBC remains in wide use today, with drivers available for most platforms and most databases. It is not uncommon to find ODBC drivers for database engines that are meant to be embedded, like [[SQLite]], as a way to allow existing tools to act as front-ends to these engines for testing and debugging.<ref>Werner, Christian (2018) [http://www.ch-werner.de/sqliteodbc/ "SQLite ODBC Driver"] {{Webarchive|url=https://web.archive.org/web/20140626165719/http://www.ch-werner.de/sqliteodbc/ |date=2014-06-26 }}, 2018-02-24</ref>

===Version history===
====ODBC specifications====
Source:<ref>{{cite web |url=http://www.easysoft.com/developer/interfaces/odbc/linux.html#odbc_versions |title=ODBC Versions |work=Linux/UNIX ODBC |publisher=Easysoft |access-date=2009-10-27 }}</ref>

*1.0: released in September 1992<ref>{{cite web |url=http://www.east.utcluj.ro/mb/mep/antal/Articole/orajdbc_2004.pdf |title=Access to an Oracle database using JDBC |first=Tiberiu Alexandru |last=Antal |publisher=Technical University of Cluj-Napoca |location=Cluj-Napoca |page=2 |access-date=2009-10-27 |quote=ODBC 1.0 was released in September 1992 |archive-url=https://web.archive.org/web/20110722071727/http://www.east.utcluj.ro/mb/mep/antal/Articole/orajdbc_2004.pdf |archive-date=2011-07-22 |url-status=dead }}</ref>
*2.0: {{circa}} 1994
*2.5
*3.0: {{circa}} 1995, John Goodson of Intersolv and Frank Pellow and Paul Cotton of IBM provided significant input to ODBC 3.0<ref>Microsoft Corporation. Microsoft ODBC 3.0 Programmer's Reference and SDK Guide, Volume 1. Microsoft Press. February 1997. ({{ISBN|9781572315167}})</ref>
*3.5: {{circa}} 1997
*3.8: {{circa}} 2009, with Windows 7<ref name="What's New in ODBC 3.8">{{cite web |url=http://msdn.microsoft.com/en-us/library/ee388580%28VS.85%29.aspx |title=What's New in ODBC 3.8 |publisher=Microsoft |access-date=2010-01-13 |quote=Windows 7 includes an updated version of ODBC, ODBC 3.8. }}</ref>
*4.0: Development announced June 2016<ref name="MSDA blog 2016-06-07">{{cite web |url=https://blogs.msdn.microsoft.com/dataaccesstechnologies/2016/06/07/a-new-release-of-odbc-for-modern-data-stores/ |title=A new release of ODBC for Modern Data Stores |last=Rukmangathan |first=Krishnakumar |work=Microsoft Data Access / SQL BI Technologies Blog |publisher=Microsoft |date=2016-06-07 |access-date=2017-01-03 |quote=After more than 15 years since the last release, Microsoft is looking at updating the Open Data Base Connectivity (ODBC) specification. }}</ref> with first implementation with SQL Server 2017 released Sep 2017 and additional desktop drivers late 2018 [https://github.com/Microsoft/ODBC-Specification final spec on Github]

====Desktop Database Drivers====
Source:<ref>{{Cite web|url=http://learn.microsoft.com/en-us/sql/odbc/microsoft/history-of-the-desktop-database-drivers?view=sql-server-ver16|title = History of the Desktop Database Drivers| date=19 January 2017 }}</ref>
*1.0 (1993–08): Used the SIMBA query processor produced by PageAhead Software.
*2.0 (1994–12): Used with ODBC 2.0.
*3.0 (1995–10): Supports Windows 95 and Windows NT Workstation or NT Server 3.51. Only 32-bit drivers were included in this release.
*3.5 (1996–10): Supports double-byte character set (DBCS), and accommodated the use of File data source names (DSNs). The Microsoft Access driver was released in an RISC version for use on Alpha platforms for Windows 95/98 and Windows NT 3.51 and later operating systems.
*4.0 (late 1998): Support Microsoft Jet Engine Unicode format along with compatibility for ANSI format of earlier versions.