Search results
Results from the WOW.Com Content Network
A candidate key is a minimal superkey, [1] i.e., a superkey that does not contain a smaller one. Therefore, a relation can have multiple candidate keys, each with a different number of attributes. [2] Specific candidate keys are sometimes called primary keys, secondary keys or alternate keys.
Educational stages are subdivisions of formal learning, typically covering early childhood education, primary education, secondary education and tertiary education.The United Nations Educational, Scientific and Cultural Organization recognizes nine levels of education in its International Standard Classification of Education (ISCED) system (from Level 0 (pre-primary education) through Level 8 ...
A key that may become the primary key. Primary The key that is selected as the primary key. Only one key within an entity is selected to be the primary key. This is the key that is allowed to migrate to other entities to define the relationships that exist among the entities.
For premium support please call: 800-290-4726 more ways to reach us
A primary source can have all of these qualities, and a secondary source may have none of them. Deciding whether primary, secondary or tertiary sources are appropriate on any given occasion is a matter of good editorial judgment and common sense, not merely mindless, knee-jerk reactions to classification of a source as "primary" or "secondary".
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 ...
Such a component or property is called a sort key. For example, the items are books, the sort key is the title, subject or author, and the order is alphabetical. A new sort key can be created from two or more sort keys by lexicographical order. The first is then called the primary sort key, the second the secondary sort key, etc.
Key takeaways. The secondary mortgage market is a financial marketplace, where investors buy and sell bundled packages consisting of many individual loans — called mortgage-backed securities.