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Set operations in SQL is a type of operations which allow the results of multiple queries to be combined into a single result set. [1] Set operators in SQL include UNION, INTERSECT, and EXCEPT, which mathematically correspond to the concepts of union, intersection and set difference.
A relational database management system uses SQL MERGE (also called upsert) statements to INSERT new records or UPDATE or DELETE existing records depending on whether condition matches. It was officially introduced in the SQL:2003 standard, and expanded [citation needed] in the SQL:2008 standard.
Microsoft SQL Server: Microsoft: 1989 2022 [22] 2022-11-16; 2 years ago Proprietary: No Microsoft SQL Server Compact (Embedded Database) Microsoft: 2000 2011 (v4.0) Proprietary: No Mimer SQL: Mimer Information Technology 1978 11.0.8E 2024-10-22 Proprietary: No MonetDB: MonetDB Foundation [23] 2004 Aug2024 [24] 2024-08-26 Mozilla Public License ...
The relational algebra uses set union, set difference, and Cartesian product from set theory, and adds additional constraints to these operators to create new ones.. For set union and set difference, the two relations involved must be union-compatible—that is, the two relations must have the same set of attributes.
A database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes and storage space to maintain the index data structure. Indexes are used to quickly locate data without having to search every row in a database table every time said table is accessed.
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ETF vs index fund: Here’s how they’re similar. ETFs and index funds are quite similar, and they can serve a lot of the same roles for the investor. Let’s look at what they have in common.
SQL includes operators and functions for calculating values on stored values. SQL allows the use of expressions in the select list to project data, as in the following example, which returns a list of books that cost more than 100.00 with an additional sales_tax column containing a sales tax figure calculated at 6% of the price.