Search results
Results from the WOW.Com Content Network
A comparison diagram is a general type of diagram, meaning a class of specific diagrams and charts, in which a comparison is made between two or more objects, phenomena or groups of data. They are a tool for visual comparison. When it comes to comparing data, five basic types of comparison can be determined. [2]
The following tables compare general and technical information for a number of relational database management systems. Please see the individual products' articles for further information. Please see the individual products' articles for further information.
For example, think of A as Authors, and B as Books. An Author can write several Books, and a Book can be written by several Authors. In a relational database management system, such relationships are usually implemented by means of an associative table (also known as join table, junction table or cross-reference table), say, AB with two one-to-many relationships A → AB and B → AB.
Crosswalk tables are often employed within or in parallel to enterprise systems, especially when multiple systems are interfaced or when the system includes legacy system data. In the context of Interfaces, they function as an internal extract, transform, load (ETL) mechanism.
A relational model organizes data into one or more tables (or "relations") of columns and rows, with a unique key identifying each row. Rows are also called records or tuples. [16] Columns are also called attributes. Generally, each table/relation represents one "entity type" (such as customer or product).
Displaying the differences between two or more sets of data, file comparison tools can make computing simpler, and more efficient by focusing on new data and ignoring what did not change. Generically known as a diff [18] after the Unix diff utility, there are a range of ways to compare data sources and display the results.
One-to-many often refer to a primary key to foreign key relationship between two tables, where the record in the first table can relate to multiple records in the second table. A foreign key is one side of the relationship that shows a row or multiple rows, with one of those rows being the primary key already listed on the first table.
A complex data model can involve hundreds of related tables. Computer scientist Edgar F. Codd created a systematic method to decompose and organize relational databases . [ 3 ] Codd's steps for organizing database tables and their keys is called database normalization , which avoids certain hidden database design errors ( delete anomalies or ...