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!
UNION
If R1 and R2 are two union compatible relations then R3 = R1 ∪ R2 is the relation having tuples that are either in R1 or in R2 or in both.
In case, R3 will have tuples such that R3 = {t | R1 ∋ t ∨ R2 ∋ t}.
Example
R1
X
Y
A1
B1
A7
B7
A2
B2
A4
B4
R2
A
B
A3
B3
R3 = R1 ∪ R2 is
Q
Note: 1) Union is a commutative operation, i.e, R ∪ S = S ∪ R.
2) Union is an associative operation, i.e.
R ∪ (S ∪ T) = (R ∪ S) ∪ T.
What is association? Give an example of association Association is used for establishing relationships among classes. Association describe links among/between classes. For exa
I have 10+ yrs exp in oracle Sql ,Pl/SQl,Forms ,Reports. I am expert in assignements & Online tutoring so i want to join you. Please guide me. Thanks Brajesh Shukla +91 9899641535
Short Note on mid Square Method of hashing? Mid square method of hashing: In the method midsquare hashing, the key is squared and the address selected from the center of the s
lock and types of lock
Question 1: a) What is the difference between a non-impact and impact printer? b) Which type of printer is generally used in a supermarket to print your receipt? Describe
Explain the two types of participation constraint. 1. Total: The participation of an entity set E in a relationship set R is said to be total if each entity in E participates i
Which are the two ways in which entities can participate in a relationship? Total and partial are the two ways in which entities can participate in a relationship
Explain ER Relationship model? An entity-relationship model (ERM): An entity-relationship model (ERM) is an abstract theoretical illustration of structured data. Entity-relatio
What is Trigger? Trigger: A database trigger is procedural code which is automatically executed in response to specific events on a particular table in a database. Triggers can
Unrepeatable reads : Assume T7 reads X twice during its implementation. If it did not update X itself it could be very disturbing to see a dissimilar value of X in its next read. B
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