Table (database)

A table is a collection of related data held in a structured format within a database. It consists of fields (columns), and rows.

In relational databases and flat file databases, a table is a set of data elements (values) using a model of vertical columns (identifiable by name) and horizontal rows, the cell being the unit where a row and column intersect. A table has a specified number of columns, but can have any number of rows. Each row is identified by one or more values appearing in a particular column subset. The columns subset which uniquely identifies a row is called the primary key.

"Table" is another term for "relation"; although there is the difference in that a table is usually a multiset (bag) of rows where a relation is a set and does not allow duplicates. Besides the actual data rows, tables generally have associated with them some metadata, such as constraints on the table or on the values within particular columns.

The data in a table does not have to be physically stored in the database. Views also function as relational tables, but their data are calculated at query time. External tables (in Informix or Oracle, for example) store data outside standard database structures but accessible to database commands.

Table

Table may refer to:

See also

Étable

Étable is a commune in the Savoie department in the Rhône-Alpes region in south-eastern France.

See also

References

HTML element

An HTML element is an individual component of an HTML document or web page, once this has been parsed into the Document Object Model. HTML is composed of a tree of HTML elements and other nodes, such as text nodes. Each element can have HTML attributes specified. Elements can also have content, including other elements and text. Many HTML elements represent semantics, or meaning. For example, the title element represents the title of the document.

In the HTML syntax, most elements are written with a start tag and an end tag, with the content in between. An HTML tag is composed of the name of the element, surrounded by angle brackets. An end tag also has a slash after the opening angle bracket, to distinguish it from the start tag. For example, a paragraph, which is represented by the p element, would be written as

However, not all of these elements require the end tag, or even the start tag, to be present. Some elements, the so-called void elements, do not have an end tag. A typical example is the br element, which represents a significant line break, such as in a poem or an address. A void element's behaviour is predefined, and it cannot contain any content or other elements. For example, the address of the dentist in the movie Finding Nemo would be written as