Of interest is an additional type of constraint that can be modeled in the Barker variant of Entity-Relationship Modeling, as implemented in the Oracle Designer CASE tool. This variant allows a relationship to b
If the database row for the related bean contains a foreign key that refers to the current bean and the foreign key has a referential integrity constraint defined, the insert will fail if the current bean's database row has not been inserted yet. Solution: Set delay-insert-until to ejb...
Key Constraint: Every relation has a designated attribute (or a concatenation thereof) which acts as the primary key for the relation in the sense that the value of its primary key identifies the tuple uniquely. 3. Entity Integrity Constraint: No primary key value can be the distinguished NULL...
If a DBMS enforces an UPDATE RESTRICT option on the referential integrity constraint between CLIENT and AGENT in the HAPPY INSURANCE database, what will be the outcome after a user tries to change the 1. To create a relationship between two tables, you need at least a data type. q...
The Entity Framework 4.0 and ASP.NET Web Forms: Getting Started Tom Dykstra Summary: In this book, you'll learn the basics of using Entity Framework Database First to display and edit data in an ASP.NET Web Forms application. Category:...
What DBMS to use? What are the typical workloads of the DBS? Build indexes to support efficient query processing. What redesign of the conceptual database schema is necessary from the point of view of efficient implementation? Overview of Database Development ...
If a DBMS enforces an UPDATE RESTRICT option on the referential integrity constraint between CLIENT and AGENT in the HAPPY INSURANCE database, what will be the outcome after a user tries to change the Consider the following snap...
If the database row for the related bean contains a foreign key that refers to the current bean and the foreign key has a referential integrity constraint defined, the insert will fail if the current bean’s database row has not been inserted yet. Solution: Set delay-insert-until to ejb...
When we store an instance of an entity in a database, we want the DBMS to ensure that the new instance has a unique identifier. This is an example of a constraint on a database, a rule to which data must adhere. The enforcement of a variety of database constraints helps us to maint...