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MySQL is an open-source relational database management system (RDBMS). Its name is a combination of "My", the name of co-founder Michael Widenius's daughter My, and "SQL", the abbreviation for Structured Query Language. A relational database organizes data into one or more data tables in which data may be related to each other; these relations help structure the data. SQL is a language programmers use to create, modify and extract data from the relational database, as well as control user access to the database. In addition to relational databases and SQL, an RDBMS like MySQL works with an operating system to implement a relational database in a computer's storage system, manages users, allows for network access and facilitates testing database integrity and creation of backups.
PostgreSQL, also known as Postgres, is a free and open-source relational database management system (RDBMS) emphasizing extensibility and SQL compliance. It was originally named POSTGRES, referring to its origins as a successor to the Ingres database developed at the University of California, Berkeley. In 1996, the project was renamed to PostgreSQL to reflect its support for SQL. After a review in 2007, the development team decided to keep the name PostgreSQL and the alias Postgres.
SQL is a domain-specific language used in programming and designed for managing data held in a relational database management system (RDBMS), or for stream processing in a relational data stream management system (RDSMS). It is particularly useful in handling structured data, i.e. data incorporating relations among entities and variables.
In the context of SQL, data definition or data description language (DDL) is a syntax for creating and modifying database objects such as tables, indices, and users. DDL statements are similar to a computer programming language for defining data structures, especially database schemas. Common examples of DDL statements include CREATE, ALTER, and DROP.
The SQL SELECT statement returns a result set of records, from one or more tables.
A data manipulation language (DML) is a computer programming language used for adding (inserting), deleting, and modifying (updating) data in a database. A DML is often a sublanguage of a broader database language such as SQL, with the DML comprising some of the operators in the language. Read-only selecting of data is sometimes distinguished as being part of a separate data query language (DQL), but it is closely related and sometimes also considered a component of a DML; some operators may perform both selecting (reading) and writing.
A data control language (DCL) is a syntax similar to a computer programming language used to control access to data stored in a database (authorization). In particular, it is a component of Structured Query Language (SQL). Data Control Language is one of the logical group in SQL Commands. SQL is the standard language for relational database management systems. SQL statements are used to perform tasks such as insert data to a database, delete or update data in a database, or retrieve data from a database.
The following tables compare general and technical information for a number of relational database management systems. Please see the individual products' articles for further information. Unless otherwise specified in footnotes, comparisons are based on the stable versions without any add-ons, extensions or external programs.
Remote database access (RDA) is a protocol standard for database access produced in 1993 by the International Organization for Standardization (ISO). Despite early efforts to develop proof of concept implementations of RDA for major commercial remote database management systems (RDBMSs), this standard has not found commercial support from database vendors. The standard has since been withdrawn, and replaced by ISO/IEC 9579:1999 - Information technology -- Remote Database Access for SQL, which has also been withdrawn, and replaced by ISO/IEC 9579:2000 Information technology -- Remote database access for SQL with security enhancement.
In SQL, null or NULL is a special marker used to indicate that a data value does not exist in the database. Introduced by the creator of the relational database model, E. F. Codd, SQL null serves to fulfil the requirement that all true relational database management systems (RDBMS) support a representation of "missing information and inapplicable information". Codd also introduced the use of the lowercase Greek omega (ω) symbol to represent null in database theory. In SQL, NULL is a reserved word used to identify this marker.
SQL:2003 is the fourth revision of the SQL database query language. The standard consists of 9 parts which are described in detail in SQL. It was updated by SQL:2006.
SQL/PSM is an ISO standard mainly defining an extension of SQL with a procedural language for use in stored procedures. Initially published in 1996 as an extension of SQL-92, SQL/PSM was later incorporated into the multi-part SQL:1999 standard, and has been part 4 of that standard since then, most recently in SQL:2016. The SQL:1999 part 4 covered less than the original PSM-96 because the SQL statements for defining, managing, and invoking routines were actually incorporated into part 2 SQL/Foundation, leaving only the procedural language itself as SQL/PSM. The SQL/PSM facilities are still optional as far as the SQL standard is concerned; most of them are grouped in Features P001-P008.
SQL/JRT, or SQL Routines and Types for the Java Programming Language, is an extension to the SQL standard first published as ISO/IEC 9075-13:2002. SQL/JRT specifies the ability to invoke static Java methods as routines from within SQL applications, commonly referred to as "Java stored procedures". SQL/JRT also calls for the ability to use Java classes as SQL structured user-defined types. The two parts of the extension originate from the earlier ANSI SQLJ part 1 and 2 standards
SQL/XML or XML-Related Specifications is part 14 of the Structured Query Language (SQL) specification. In addition to the traditional predefined SQL data types like NUMERIC, CHAR, TIMESTAMP, ... it introduces the predefined data type XML together with constructors, several routines, functions, and XML-to-SQL data type mappings to support manipulation and storage of XML in a SQL database.
SQL:1999 was the fourth revision of the SQL database query language. It introduced many new features, many of which required clarifications in the subsequent SQL:2003. In the meanwhile SQL:1999 is deprecated.
A hierarchical query is a type of SQL query that handles hierarchical model data. They are special cases of more general recursive fixpoint queries, which compute transitive closures.
PL/SQL is Oracle Corporation's procedural extension for SQL and the Oracle relational database. PL/SQL is available in Oracle Database, Times Ten in-memory database, and IBM Db2. Oracle Corporation usually extends PL/SQL functionality with each successive release of the Oracle Database.
SQL:2011 or ISO/IEC 9075:2011 is the seventh revision of the ISO (1987) and ANSI (1986) standard for the SQL database query language. It was formally adopted in December 2011. The standard consists of 9 parts which are described in detail in SQL. The next version is SQL:2016.
The syntax of the SQL programming language is defined and maintained by ISO/IEC SC 32 as part of ISO/IEC 9075. This standard is not freely available. Despite the existence of the standard, SQL code is not completely portable among different database systems without adjustments.
GQL is a proposed standard graph query language. In September 2019 a proposal for a project to create a new standard graph query language was approved by a vote of national standards bodies which are members of ISO/IEC Joint Technical Committee 1(ISO/IEC JTC 1). JTC 1 is responsible for international Information Technology standards. GQL is intended to be a declarative database query language, like SQL.
References
- 1 2 SQL:2008 now an approved ISO International Standard Archived 2011-06-28 at the Wayback Machine , a July 29th, 2008 blog post from a Sybase blog
- ↑ Oracle Compliance To Core SQL:2008 from Oracle Corporation