As a result, the different variants of extended SQL offered by vendors are not fully compatible with one another. Commercial vendors offer proprietary extensions to differentiate their product offerings by giving customers additional features and functions. For example, Microsoft offers a set of extensions called Transact-SQL, while Oracle's extended version of the standard is Procedural Language for SQL. Some versions of SQL include proprietary extensions to the standard language for procedural programming and other functions. SQL-compliant database server products include the following: The current ISO standard for SQL is ISO/IEC 9075:2016.īoth proprietary and open source RDBMSes built around SQL are available for use by organizations. The standard way of referring to an ISO standard version is to use the standards organizations - ISO/IEC - followed by the ISO standard number, a colon and the publication year. ISO/IEC 9075 is the ISO SQL standard developed jointly by ISO and the International Electrotechnical Commission. New versions of the SQL standard are published every few years, the most recent in 2016. The SQL query language can be used for relational or nonrelational databases, but it offers advantages for relational databases.Īn official SQL standard was adopted by the American National Standards Institute ( ANSI) in 1986, with the International Organization for Standardization ( ISO) adopting the standard in 1987. SQL became the de facto standard programming language for relational databases after they emerged in the late 1970s and early 1980s. A table used to track customer contacts usually uses a unique customer identifier called a key or primary key to reference the customer's record in a separate table used to store customer data, such as name and contact information. For example, a SQL database used for customer service can have one table for customer names and addresses and other tables that hold information about specific purchases, product codes and customer contacts. Relational databases are relational because they are composed of tables that relate to each other.
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