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SQL: Standards and Flavors A presentation for CS157B by David Wortham SQL Definition • SQL: Structured Query Language • Invented in 1974 by Donald Chamberlin and Raymond Boyce for IBM • Used for creation and modification of Relational DataBase data and schema • Multiple Standard Revisions and Multiple Flavors (Implementations) exist Standard Revisions Differences: • Revisions successively introduced additional features • Revisions are mostly BackwardsCompatible with older standards Similarities: • Ratified by Standards Organizations • Incompletely implemented by vendors Standard Revisions and Dates of Standardization • SEQUEL/Original SQL - 1974 • SQL-86 (ANSI/ISO) - 1986 • SQL-92 - 1992 • SQL:1999 - 1999 • SQL:2003 - 2003 • SQL:2006 - 2006 Standards Revisions: SEQUEL • Original definition of SQL • Mostly defined data manipulation and schema definition controls Standards Revisions: SQL-86 • Ratification and acceptance of a formal SQL standard by ANSI and ISO Standards Revisions - SQL:92 • New datatypes: DATE, TIME, TIMESTAMP, INTERVAL, VARCHAR • New scalar operations: string concatenation, date and time mathematics • New set operations: UNION JOIN, NATURAL JOIN • Schema changes via ALTER and DROP • Among others… Standards Revisions - SQL:99 • Adds User Defined Types (UDTs) to SQL • Among others… Standards Revisions - SQL:2003 • XML-related features • MERGE statement defined • SEQUENCE generation • Among others… Standards Revisions – SQL:2006 • Increased support for XML • Support for XQuery, an XML-SQL interface standard Flavors of SQL • Most implementations do not implement the entire standard • Schemas and Stored Procedures for different flavors are rarely portable • Timestamp data types are usually proprietary Common Flavors: • Oracle • MySQL • SQLite • Postgres • MSQL (Microsoft) • Microsoft Access Flavors: Stored Procedure Support Common Procedural Languages (PLs): • ANSI/ISO Standard: SQL/PSM • IBM: SQL PL • Microsoft/Sybase: T-SQL • MySQL: MySQL • Oracle: PL/SQL • PostgreSQL: PL/pgSQL Flavors: MySQL 5.x MySQL 5.x Implements most of SQL:99 standard including: • Stored Procedures • Triggers • XA transactions Flavors: Oracle 10g Release 2 • Implements much of SQL:2003 • Complete Listing of CORE feature support: http://download-east.oracle.com/docs/cd/B19306_01/server.102/b14200/ap_standard_sql003.htm Flavors: SQLite 3.x SQLite 3.x Implements most of SQL:92 standard except: • FOREIGN KEY constraints • Complete trigger support • Complete ALTER TABLE support • Nested transactions • RIGHT and FULL OUTER JOIN • Writing to VIEWs • GRANT and REVOKE Flavors: PostgreSQL 8.4 • Implements most of SQL:2003 except: • MERGE statement • Assertions, Subqueries in CHECK • Some flagging features • Many array features • BLOB data type • Comprehensive list: http://developer.postgresql.org/pgdocs/postgres/unsupported-features-sql-standard.html Vendor MarketShare 1 Source: JoinVision E-Services GmbH, July 2006 Vendor MarketShare 2 "Relational Databases Rule the Roost”, SD Times in July 2004 References • • • • MySQL :: MarketShare http://www.mysql.com/why-mysql/marketshare/ SQL:1999 http://www.service-architecture.com/database/articles/sql1999.html PostgreSQL supported and unsupported standard features http://developer.postgresql.org/pgdocs/postgres/features-sql-standard.html http://developer.postgresql.org/pgdocs/postgres/unsupported-features-sql-standard.html SQL Features That SQLite Does Not Implement http://www.sqlite.org/omitted.html
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