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For this example it is assumed that each book has only one author. A table that conforms to the relational model has a primary key which uniquely identifies a row. In our example, the primary key is a composite key of {Title, Format} (indicated by the underlining):
Query by Example (QBE) is a database query language for relational databases. It was devised by Moshé M. Zloof at IBM Research during the mid-1970s, in parallel to the development of SQL . [ 1 ] It is the first graphical query language, using visual tables where the user would enter commands, example elements and conditions.
This list includes SQL reserved words – aka SQL reserved keywords, [1] [2] as the SQL:2023 specifies and some RDBMSs have added. Reserved words in SQL and related products In SQL:2023 [ 3 ]
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...
For example, the shapefile format, developed by ESRI for spatial data in its PC ArcInfo geographic information system, uses .dbf files to store feature attribute data. [44] Microsoft recommends saving a Microsoft Works database file in the dBase file format so that it can be read by Microsoft Excel. [45] A package is available for Emacs to read ...
A foreign key is a set of attributes in a table that refers to the primary key of another table, linking these two tables. In the context of relational databases, a foreign key is subject to an inclusion dependency constraint that the tuples consisting of the foreign key attributes in one relation, R, must also exist in some other (not necessarily distinct) relation, S; furthermore that those ...
A data visualisation tool that originally shipped as part of SQL Server 2012, later an add-in for Microsoft Excel [142] SQL14 SQL Server 2014 Version 12 [143] Hekaton: SQL Server In-Memory OLTP In-memory database engine built into SQL Server 2014 [144] SQL16 SQL Server 2016 Version 13 [145] Helsinki SQL Server 2017 Version 14 [146] [147] Seattle