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Presence check Checks that data is present, e.g., customers may be required to have an email address. Range check Checks that the data is within a specified range of values, e.g., a probability must be between 0 and 1. Referential integrity Values in two relational database tables can be linked through foreign key and primary key.
SELECT list is the list of columns or SQL expressions to be returned by the query. This is approximately the relational algebra projection operation. AS optionally provides an alias for each column or expression in the SELECT list. This is the relational algebra rename operation. FROM specifies from which table to get the data. [3]
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 ...
FuelPHP, ORM and framework for PHP, released under the MIT license. Based on the ActiveRecord pattern. Laminas, framework that includes a table data gateway and row data gateway implementations; Qcodo, ORM and framework, open source; Redbean, ORM layer for PHP, for creating and maintaining tables on the fly, open source, BSD
Web-based, for PHP and MySQL/MariaDB Zotero: Roy Rosenzweig Center for History and New Media at GMU: 2006 2024-08-26 7.0.3 [6] Free / Online storage free up to 300 MB / Additional storage space available Yes AGPL: Multi-platform desktop version with connectors for Firefox, Chrome and Safari. Web-based access to reference library also available ...
Goat Cheese, Pecan, and Mixed Green Salad. This premade salad consists of mixed greens, pecans, dried cranberries, bell peppers, tomatoes, red onions, and goat cheese with a honey vinaigrette. The ...
No two distinct rows or data records in a database table can have the same data value (or combination of data values) in those candidate key columns since NULL values are not used. Depending on its design, a database table may have many candidate keys but at most one candidate key may be distinguished as the primary key.
Make this iPad someone's go-to gadget for work, play and everything in between. With a stunning 10.9-inch display, 64GB of storage, and lightning-fast performance, this gadget multitasks like a ...