Search results
Results from the WOW.Com Content Network
The hash join is an example of a join algorithm and is used in the implementation of a relational database management system.All variants of hash join algorithms involve building hash tables from the tuples of one or both of the joined relations, and subsequently probing those tables so that only tuples with the same hash code need to be compared for equality in equijoins.
Some database systems allow the user to force the system to read the tables in a join in a particular order. This is used when the join optimizer chooses to read the tables in an inefficient order. For example, in MySQL the command STRAIGHT_JOIN reads the tables in exactly the order listed in the query. [16]
The recursive join is an operation used in relational databases, also sometimes called a "fixed-point join". It is a compound operation that involves repeating the join operation, typically accumulating more records each time, until a repetition makes no change to the results (as compared to the results of the previous iteration).
where v is a tuple variable, H a header and f(v) a formula in F[S,type] where type = { (v, H) } and with v as its only free variable. The result of such a query for a given database db over S is the set of all tuples t over D with dom(t) = H such that f is true for db and val = { (v, t) }. Examples of query expressions are:
PHP and MySQL Programming/Print version - Wikibooks, open books for an open world; Author: hbossot: Image title: File change date and time: 22:12, 9 September 2016: Date and time of digitizing: 22:12, 9 September 2016: Software used: PDFCreator 2.2.2.0: Conversion program: PDFCreator 2.2.2.0: Encrypted: no: Page size: 595 x 842 pts (A4) Version ...
RDFLib is a Python library for working with RDF, [2] a simple yet powerful language for representing information. This library contains parsers/serializers for almost all of the known RDF serializations, such as RDF/XML, Turtle, N-Triples, & JSON-LD, many of which are now supported in their updated form (e.g. Turtle 1.1).
Note (3): "For other than InnoDB storage engines, MySQL Server parses and ignores the FOREIGN KEY and REFERENCES syntax in CREATE TABLE statements. The CHECK clause is parsed but ignored by all storage engines." [73] Note (4): Support for Unicode is new in version 10.0. Note (5): MySQL provides GUI interface through MySQL Workbench.
A current version is maintained for the table, or possibly a group of tables. This is stored in a supporting construct such as a reference table. When a change capture occurs, all data with the latest version number is considered to have changed. Once the change capture is complete, the reference table is updated with a new version number.