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In addition to basic equality and inequality conditions, SQL allows for more complex conditional logic through constructs such as CASE, COALESCE, and NULLIF.The CASE expression, for example, enables SQL to perform conditional branching within queries, providing a mechanism to return different values based on evaluated conditions.
Examples of these include the geographic information system (GIS) data types from the PostGIS project for PostgreSQL. There is also a data type called a domain , which is the same as any other data type but with optional constraints defined by the creator of that domain.
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 ...
Wherever logic is applied, especially in mathematical discussions, it has the same meaning as above: it is an abbreviation for if and only if, indicating that one statement is both necessary and sufficient for the other. This is an example of mathematical jargon (although, as noted above, if is more often used than iff in statements of definition).
The oblique case in pronouns has three subdivisions: Regular, Ergative, and Genitive. There are eight case-marking postpositions in Hindi and out of those eight the ones which end in the vowel -ā (the semblative and the genitive postpositions) also decline according to number, gender, and case.
The syntax of the SQL programming language is defined and maintained by ISO/IEC SC 32 as part of ISO/IEC 9075.This standard is not freely available. Despite the existence of the standard, SQL code is not completely portable among different database systems without adjustments.
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 ...
EnterpriseDB (EDB) is an American company that provides software and services based on the open-source database PostgreSQL (also known as Postgres), and is one of the largest contributors to Postgres. [2] EDB develops and integrates performance, security, and manageability enhancements into Postgres to support enterprise-class workloads.