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Typically, grouping is used to apply some sort of aggregate function for each group. [1] [2] The result of a query using a GROUP BY statement contains one row for each group. This implies constraints on the columns that can appear in the associated SELECT clause. As a general rule, the SELECT clause may only contain columns with a unique value ...
Snapshot fact tables record facts at a given point in time (e.g., account details at month end) Accumulating snapshot tables record aggregate facts at a given point in time (e.g., total month-to-date sales for a product) Fact tables are generally assigned a surrogate key to ensure each row can be uniquely identified. This key is a simple ...
MySQL (/ ˌ m aɪ ˌ ɛ s ˌ k juː ˈ ɛ l /) [6] is an open-source relational database management system (RDBMS). [6] [7] Its name is a combination of "My", the name of co-founder Michael Widenius's daughter My, [1] and "SQL", the acronym for Structured Query Language.
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 ...
WebScaleSQL – software branch of MySQL 5.6 jointly developed by Facebook, Google, LinkedIn and Twitter to provide a centralized development structure for extending MySQL with new features specific to large-scale deployments, such as building large replicated databases running on server farms. The project's objective is to tightly follow new ...
MySQL is a multithreaded, multi-user, SQL database management system, [9] acquired by Sun Microsystems in 2008, which was then acquired by Oracle Corporation in 2010. [10] Since its early years, the MySQL team has made its source code available under the terms of the GNU General Public License , as well as under a variety of proprietary agreements.
InnoDB is a storage engine for the database management system MySQL and MariaDB. [1] Since the release of MySQL 5.5.5 in 2010, it replaced MyISAM as MySQL's default table type. [2] [3] It provides the standard ACID-compliant transaction features, along with foreign key support (declarative referential integrity).
MariaDB is intended to maintain high compatibility with MySQL, with exact matching with MySQL APIs and commands, allowing it in many cases to function as a drop-in replacement for MySQL. However, new features are diverging. [ 7 ]