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Explain Derived and Non-Derived Attribute?
In few cases, two or more attribute values are related, for instance, Age and BirthDate attributes of a person. For specific person entity, the value of Age can be determined from the current date and the value of that person's BirthDate. Therefore, the attribute Age is known as derived attribute and the attribute BirthDate is known as non-derived or stored attribute.
When is a transaction rolled back? Any changes that the aborted transaction made to the database must be uncompleted. While the changes caused by an aborted transaction have be
East Coast Aquarium Relational Database
What is called query processing? Query processing refers to the range of activities included in extracting data from a database.
Consider the relations described below: PHYSICIAN (regno, name, telno, city) PATIENT (pname, street, city) VISIT (pname, regno, date_of_visit, fee) Where the regno and pname ide
Cardinality of Relationship One-to-One Only one entity of the first set is linked to only one entity of the second set. E.g. A teacher teaches a student. Only one teacher
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
What is the use of integrity constraints? Integrity constraints make sure that changes made to the database by authorized users do not result in a loss of data consistency. The
Having Clause with sub queries: First we have to recollect the GROUP BYclause. The following query searches the minimum salary in every department. SELECT DEPTNO, MIN (SAL)
How are tables stored on Disk? We realise that every record of a table can have different amounts of data. This is due to in some records; some attribute values may be "zero".
List the set operations of SQL? 1) Union 2) Intersect operation 3) The except operation
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