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!
Dependency Preservation
It is obvious that the decomposition must be lossless so that we do not lose any information from the relation that is decomposed. Dependency preservation is another main requirement since a dependency is a constraint on the database. If each attributes appearing on the left and the right side of a dependency appear in the similar relation, then a dependency is considered to be preserved. Therefore, dependency preservation can be checked simply. Dependency preservation is important, because as stated previously, dependency is a constraint on a relation. Therefore, if a constraint is split over more than one relation (dependency is not preserved), the constraint would be complex to meet. We will not talk about this in more detail in this unit. You may refer to the more readings for more details. Though, let us state one basic point:
"A decomposition into 3NF is lossless and dependency preserving whereas a decomposition into BCNF is lossless but may or may not be dependency preserving."
Describe the benefits of OOD techniques OOD techniques are very useful for development of large and complex systems. It has been noted that large projects that are developed u
Explain the term- Query. Queries are used to repossess and show specific records in a table. They can also be used to show specific fields of specific records, which meet the co
Which data type can store unstructured data? Raw data type can store unstructured data.
What is known as fudge factor? The number of partitions is enhanced by a small value called the fudge factor, which is usually 20 percent of the number of hash partitions compu
Vertical Fragmentation- Vertical fragmentation groups together only those attributes in a relation that are used jointly by various important transactions. A vertical fragment is d
What are the various symbols used to draw an E-R diagram? Explain with the help of an example how weak entity sets are represented in an E-R diagram. Various symbols used to d
# ???? ..
Which is a valid SQL type? A valid SQL Should be in CHARACTER it is should be NUMERIC and FLOAT.
What is called block-level striping? Block level striping stripes blocks across many disks. It treats the array of disks as a large disk, and provides blocks logical numbers
Define outer union operation of the relational algebra. Compute the outer union for the relations R and S given below. Outer Join - If there are any values in one tabl
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