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Explain Relational model and their use in DBMS?
Relational Model - The relational model was first introduced through E.F. Codd of the IBM Research in the year of 1970. The model uses the concept of a mathematical relation (like a table of values) as its primary building block, and has its theoretical basis in set theory and first-order predicate logic. The relational model presents the database as a collection of relations.
Consider the relations City (city_name, state) Hotel (name, address) City_hotel (hotel_name, city_name, owner) Answer the following queries in relational algebra (i) Find
Describe DROP TABLE command of SQL along with both the options - CASCADE and RESTRICT. DROP TABLE command - This command drops the specified table. Dropping a table also dro
Define the concept of aggregation. Give two examples where this concept is useful. Ans: Aggregation transforms a relationship among the objects into a higher-level object. A
What are domain constraints? A domain is a set of values that might be assigned to an attribute .all values that appear in a column of a relation must be taken from the similar
Define query optimization. Query optimization refers to the process of search the lowest -cost method of evaluating a given query.
Describe the types of attributes? Types of attributes: An attribute's category determines the type of values that are permitted in the attribute. For instance, the value vers
Explain trivial dependency? Functional dependency of the form α ->β. is trivial if α C β. Trivial functional dependencies are satisfied by all the relations.
Process of Adjustment of inheritance During object design, inheritance is readjusted by rearranging classes and operations, and abstracting common behaviour.
What are audit trails? An audit trail is a log of all alters to the database along with information like which user performed the change and when the alter was performed.
What are the advantages of creating a table from existing table?
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