Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
It defines that no primary key value can be null. This is as the primary key is used to recognize individual tuple in the relation. So we will not be able to recognize the records uniquely containing null values for the primary key attributes. This constraint is specified on single individual relation.
Example: Let R be the Table
A#
B
C
Null
B1
C1
A2
B2
C2
B3
C3
A4
B4
A5
C5
Note:
1) '#' shows the Primary key of a relation.
In the relation R above, the primary key has null values in the tuples t1 & t3. NULL value in primary key is not allowed, therefore, relation instance is an invalid instance.
Define the Wait for graph Ans: The wait-for-graph is a directed graph and consist of nodes and directed arcs; the nodes of the graph are active transactions. An arc of the grap
What is vertical fragmentation? Vertical fragmentation divides the relation by decomposing the scheme R of relation r.
What is the difference among a database schema and a database state? The collection of information stored in database at particular moment in time is known as database state a
Australian Bureau of Statistics (ABS) provides retail data for different groups and different states as well as the aggregate numbers. Table 11 " Retail Turnover, State by Industry
What do you understand by RAID? Explain RAID Level 4 and Level5? RAID - It is stands for Redundant Array of Inexpensive Disks (as named by the inventor), or alternatively Re
Explain Strict Two-Phase locking A transaction T does not release any type of its exclusive (X) locks until that transaction commits or aborts. In this method no other transact
write-set(T): Each data items that are written by a transaction T
Define decision tree classifiers? As the name suggests decision tree classifiers use a tree: Every leaf node has an associated class, and every internal node has a predicate as
Give an example of enforcement in Typing. You can understand the idea of enforcement as it makes sure objects of dissimilar classes may not be interchanged as below: Exampl
What is a data dictionary? Data Dictionary is a main source of data in a data management system. Its major function is to carry the creation and management of data definition
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd