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Explain weak and strong entity sets?
Weak and Strong entity sets: A physically powerful entity set has a primary key. All tuples in the group are distinguishable through that key. A weak entity set has no primary key unless attributes of the tough entity set on which it depends are included. Tuples in a weak entity grouped are partition according to their relationship along with tuples within a strong entity set. Tuples inside each partition are discernible by a discriminator, that is a set of attributes. A strong entity set has a primary key. All tuples within the set are distinguishable through that key. A weak entity set has no primary key unless attributes of the strong entity set on that it depends are included. Tuples in a weak entity set are partitioned according to their relationship along with tuples in a strong entity set. Tuples within each partition are discernible through a discriminator that is a set of attributes.
what is meant semantic query optimization? how does it differ from other query optimization techniques?
Define query optimization. Query optimization refers to the process of search the lowest -cost method of evaluating a given query.
Explain the disadvantages of creating a temporary table? If you have already created a temporary table with a shown name and attempting to create a second one with that nam
What is a data dictionary? A data dictionary is a data structure which keeps Meta data about the structure of the database i.e. the schema of the database.
What is multiplicity in the associations? Give an example to explain multiplicity? Multiplicity in association indicate number of objects participate in any relationship. For
Consider the following frequency counts of some itemsets in a transaction database r : freq({A}, r) = 0.405 freq({B}, r) = 0.510 freq({C}, r) = 0.303 freq({A
Given the following set of functional dependencies {cf?bg, g?d, cdg?f, b?de, d?c} defined on R(b,c,d,e,f,g) a.Find a non-redundant cover. b.Find a canonical cover.
What is a view? Make a view of EMP table named DEPT 20, to display the employees in department 20 and their annual salary. Ans: View is a virtual table that does not consist
What is equi join? Equi Join - It generates all the combinations of tuples from two relations which satisfy a join condition along with only equality comparison (=).
QUESTION (a)(i) Define the term database. (ii) How is it different from a database management system? (b) What is the difference between an entity and an attribute? (c
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