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What is a view in SQL? When can views be updated?
A view is a virtual table which consists of columns from one or more tables. Through it is same to a table; it is stored in the database. It is a query stored as an object. Therefore, a view is an object in that derives its data from one or more tables. These tables are referred to as base or underlying tables.
Views can be updated if they are described on a single table without any aggregate functions could be mapped to an update on the underlying base table under certain conditions.
Give the levels of data abstraction? There are three levels of Data Abstraction a) Physical level b) logical level c) view level
Why is database design important?
what is view?explain
Read the description below and draw an Entity-Relationship diagram for it. You must use the symbols described in the course materials. This database will help the Parents Assocc
Consistency error : These errors happen due to the inconsistent state of database caused may be due to wrong implementation of commands or in case of a transaction abort. To overc
An instance of relational schema R (A, B, C) has distinct values of A including NULL values. then A is a candidate key or not? If relational schema R (A, B, C) has distinct val
A domain is a set of permissible values that can be given to an attribute. So each attribute in a table has a definite domain. Values to these attributes cannot be assigned outside
Consider the relation PERSON. If you want to display details of persons having age less than or equal to 30 than the select operation will be used as follows: σ AGE The resu
Attributes that are directly kept in the data base. For example, 'Birth date' attribute of a person. Derived Attributes that are not stored directly but can be derived
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
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