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 the tuple in one relation that refers to another relation must refer to an existing tuple in that relation. This constraint is states on two relations (not essentially distinct). It uses a concept of foreign key and has been dealt with in more factors in the next unit.
Example
In the example given above, the value of C^ in every R tuple is matching with the value of C# in some S tuple. If a tuple has values (A6, B2, and C4) is added then it is invalid as referenced relation S doesn't contain C4. Therefore, it will be a violation of referential integrity constraint.
What is NULL? Simply NULL means not in value.
What do you mean through integrity constraints? Integrity Constraints -An integrity constraint is a condition specified on a database schema and restricts the data in which
What is System R? What are its two major subsystems? System R was intended and developed over a period of 1974-79 at IBM San Jose Research Center. It is a prototype and its pur
Wait-die" scheme : The idea is based on non-preventive method. It is based on a simple rule: If Ti requests a database resource that is held by T
What is a primary key? Primary key is chosen by the database designer as the principal means of identifying an entity in the entity set.
1. Create a subroutine that does the remote blast on the file protein.fa. 2. Pass that returned files from the blast to another subroutine that parses the output and sends it to
A well-maintained relational DBMS has a high level of data integrity. What features of a relational DBMS contribute towards this level of integrity? Relational DBMS gives high
Explain three main attributes of data.
Primary Index In primary index, there is a one-to-one relationship among the entries in the index table and the records in the major table. Primary index can be of two types:
What is meant by functional dependencies? Consider a relation schema R and α C R and β C R. The functional dependency α ->β holds on relational schema R if in any legal relati
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