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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 out the names and address of hotels in Agra.(ii) List the names of cities that have no hotel.(iii) List the names of the hotels owned through ‘Taj Group'.
Ans: (i) Π name, address ( σ city_name= ‘Agra' (Hotelname=city_name City_hotel))(ii) Π city_name (City) - Π city_name(City_hotel)(iii) Π hotel_name ( σ owner='Taj Group' (City_hotel))
Operator Precedence The basic operators used in SQL are * / - + Operators of the similar priority are evaluated From Left to right Parentheses are used to force priorit
Table_Name( attribute_1, attribute_2, attribute_3, ….. ,attribute_x) Primary Key ( attribute_1, attribute_2) Foreign Key attribute_4 References Table_Name_2 (repeat for each fore
Demonstrate the UML model Using UML, it is possible to generate code in any of the programming language from UML model (called forward engineering) and rebuild a model from an
When It is better to use files than a DBMS? It is better to use files than a DBMS when Multiple users wish to access the data.
Ancestry database records information about family trees . Following information is recorded about each person: FIRSTNAME first name SURNAME surname MNAME maiden name (if
Define deadlock avoidance. An alternative method for avoiding deadlocks is to needs additional information about how resources are to be requested. Each request requires the s
Explain recovery process after system failure using checkpoint. Ans: Checkpoint scheme or method is an extra component of the log based recovery system. This scheme is used to
Explain the two constraints, check and foreign key in SQL along with an example for each. Give the syntax. CHECK constraint - CHECK constraint specifies an expression which
It defines that no primary key value can be null. This is as the primary key is used to recognize individual tuple in the relation. So we will not be able to recognize the records
Define the terms 1) physical schema 2) logical schema. Physical schema: The physical schema explains the database design at the physical level, which is the lowest level of abs
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