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Query by Example (QBE) is a database query language for relational databases. It was devised by Moshé M. Zloof at IBM Research during the mid-1970s, in parallel to the development of SQL . [ 1 ] It is the first graphical query language, using visual tables where the user would enter commands, example elements and conditions.
Sample binary-state checkboxes, with some options disabled. A checkbox (check box, tickbox, tick box) is a graphical widget that allows the user to make a binary choice, i.e. a choice between one of two possible mutually exclusive options. For example, the user may have to answer 'yes' (checked) or 'no' (not checked) on a simple yes/no question.
Check constraints are used to ensure the validity of data in a database and to provide data integrity. If they are used at the database level, applications that use the database will not be able to add invalid data or modify valid data so the data becomes invalid, even if the application itself accepts invalid data.
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.
Angular 2.0 was announced at the ng-Europe conference 22–23 October 2014. [17] On April 30, 2015, the Angular developers announced that Angular 2 moved from Alpha to Developer Preview. [18] Angular 2 moved to Beta in December 2015, [19] and the first release candidate was published in May 2016. [20] The final version was released on 14 ...
SQLite (/ ˌ ɛ s ˌ k juː ˌ ɛ l ˈ aɪ t /, [4] [5] / ˈ s iː k w ə ˌ l aɪ t / [6]) is a free and open-source relational database engine written in the C programming language.It is not a standalone app; rather, it is a library that software developers embed in their apps.
Example of an object-oriented model [1] An object database or object-oriented database is a database management system in which information is represented in the form of objects as used in object-oriented programming. Object databases are different from relational databases which are table-oriented.
For example, if there are multiple tabs on a page, the pure DHTML approach would load the contents of all tabs and then dynamically display only the one that is active, while AJAX could load each tab only when it is really needed.