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Define entity integrity and referential integrity. How does SQL allow specification of these?
Ans: Entity Integrity Rule- If the attribute A of relation R is a prime attribute of R after that A cannot accept null values.
Referential Integrity Rule- In referential integrity, it is made sure that a value that appears in one relation for a given set of attributes as well appears for a particular set of attributes in another relation.
In SQL, referential integrity and entity integrity rules are implemented as constraints on the relation known as reference Key constraint and primary Key constraint correspondingly.
These constraints can be fixed with relation at the time of creation of the relations or after the creation of the relations by altering the definition of the relations. For instance:
1. Staff(staffID, firstName, lastName, availabilityID, experience, phone, mobile, email); 2. Availability(availabilityID, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday,
Related fields in a database are grouped in which form? Related data fields in a database are grouped to form a data record. (A record is a collection of related fields)
Mention various steps required to draw an E-R Diagram. Draw an E-R Diagram for Student Information System. Mention all suitable assumptions to justify your answer.
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Consider the entity type dependent related to employee entity, which is used to keep track of the dependents of every employee. The attributes of dependents are: name, sex, birth d
The participation Constraints shows whether the existence of an entity depends on its being associated to another entity by the relationship type. There are two kinds of participat
WHY SHOULD NULL IN A RELATION BE AVOID AS possible?
Concurrency issues Data integrity: Threads accessing same object need to be synchronized, such as: banking account. Deadlock: One or more threads in system are perman
Example- Search the salary of employees who are not 'ANALYST' but get a salary below than or equal to any people employed as 'ANALYST'. SELECT EMPNO, ENAME, JOB, SAL FROMEMP
(a) Data Mining Process : In the context of this cluster analysis project , and in your own words , explain how you would execute the first stage of data mining, namely the "P
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