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In SQL (Structured Query Language), the term cardinality refers to the uniqueness of data values contained in a particular column (attribute) of a database table. The lower the cardinality, the more duplicated elements in a column. Thus, a column with the lowest possible cardinality would have the same value for every row.
A table (called the referencing table) can refer to a column (or a group of columns) in another table (the referenced table) by using a foreign key. The referenced column(s) in the referenced table must be under a unique constraint, such as a primary key. Also, self-references are possible (not fully implemented in MS SQL Server though [5]).
For example, jQuery can be used for finding an element in the document with a certain property (e.g. all elements with the h1 tag), changing one or more of its attributes (e.g. color, visibility), or making it respond to an event (e.g. a mouse click).
The data-theme attribute tells the browser what theme to render. The data-add-back-btn attribute adds a back button to the page if set to true. Lastly, icons can be added to elements via the data-icon attribute. jQuery Mobile has fifty commonly-used icons built in. A brief explanation of the Data Attributes used in this example:
A derived table is a subquery in a FROM clause. Essentially, the derived table is a subquery that can be selected from or joined to. Derived table functionality allows the user to reference the subquery as a table. The derived table also is referred to as an inline view or a select in from list.
In the relational model of databases, a primary key is a designated attribute that can reliably identify and distinguish between each individual record in a table.The database creator can choose an existing unique attribute or combination of attributes from the table (a natural key) to act as its primary key, or create a new attribute containing a unique ID that exists solely for this purpose ...
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 ...
The table above (even if some more columns are added) maintains one line per country for narrower browser and screen widths. So it is therefore more readable and scannable in long country tables. The table format below can greatly increase in number of lines, and require more vertical scrolling, especially if more columns are added.