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The INTERSECT operator removes duplicate rows from the final result set. The INTERSECT ALL operator does not remove duplicate rows from the final result set, but if a row appears X times in the first query and Y times in the second, it will appear (,) times in the result set.
Queries can be nested so that the results of one query can be used in another query via a relational operator or aggregation function. A nested query is also known as a subquery. While joins and other table operations provide computationally superior (i.e. faster) alternatives in many cases, the use of subqueries introduces a hierarchy in ...
PostgreSQL was originally named POSTGRES, referring to its origins as a successor to the Ingres database developed at the University of California, Berkeley. [26] [27] In 1996, the project was renamed PostgreSQL to reflect its support for SQL. After a review in 2007, the development team decided to keep the name PostgreSQL and the alias ...
A set intersection oracle (SIO) is a data structure which represents a collection of sets and can quickly answer queries about whether the set intersection of two given sets is non-empty. The input to the problem is n finite sets. The sum of the sizes of all sets is N (which also means that there are at most N distinct elements). The SIO should ...
The intersect operation satisfies a weaker property: the false positive probability in the resulting Bloom filter is at most the false-positive probability in one of the constituent Bloom filters, but may be larger than the false positive probability in the Bloom filter created from scratch using the intersection of the two sets.
Reserved words in SQL and related products In SQL:2023 [3] In IBM Db2 13 [4] In Mimer SQL 11.0 [5] In MySQL 8.0 [6] In Oracle Database 23c [7] In PostgreSQL 16 [1] In Microsoft SQL Server 2022 [2]
PostgreSQL and some other databases have support for foreign schemas, which is the ability to import schemas from other servers as defined in ISO/IEC 9075-9 (published as part of SQL:2008). This appears like any other schema in the database according to the SQL specification while accessing data stored either in a different database or a ...
PL/pgSQL (Procedural Language/PostgreSQL) is a procedural programming language supported by the PostgreSQL ORDBMS. It closely resembles Oracle 's PL/SQL language. Implemented by Jan Wieck, PL/pgSQL first appeared with PostgreSQL 6.4, released on October 30, 1998. [ 1 ]