PACE, which offered its data dictionary, excellent referential integrity, and speedy application development, was in the process of being ported to UNIX under the name OPEN Pace.
22.
One solution is to recast disparate databases to integrate these databases without the need for ETL . The recast databases support commonality constraints where referential integrity may be enforced between databases.
23.
A key is essentially a pointer, a foreign key is a field of one struct that points to another struct, and referential integrity means that there are no dangling pointers.
24.
The primary keys and unambiguously role-named foreign keys expressed sometimes subtle uniqueness and referential integrity constraints that needed to be known and honored by whatever type of database was ultimately designed.
25.
Even current relational databases " do not allow referential integrity constraints to span databases . " There are few systems that maintain both ACID transactions and X / Open XA standards for distributed transaction processing.
26.
Some relational database management systems ( RDBMS ) can enforce referential integrity, normally either by deleting the foreign key rows as well to maintain integrity, or by returning an error and not performing the delete.
27.
:: : In principle, there's nothing stopping you from doing this; the only problem is that you won't be able to set up proper foreign key constraints to enforce referential integrity.
28.
EAV systems trade off simplicity in the physical and logical structure of the data for complexity in their metadata, which, among other things, plays the role that database constraints and referential integrity do in standard database designs.
29.
For referential integrity to hold in a relational database, any column in a base table that is declared a foreign key can contain either a null value, or only values from a parent table's primary key or a candidate key.
30.
If a referential integrity constraint is defined to the effect that { Shop Type, Nearest Shop } from the first table must refer to a { Shop Type, Shop } from the second table, then the data anomalies described previously are prevented.
