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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:
Which operation is used if we are interested in only certain columns of a table? PROJECTION operation is used if we are interested in only certain columns of a table.
Create Student DB and execute Insert query? STUDENT (name, student#, class, major) COURSE (course name, course#, credit hours, department) SECTION (section identifier, course
Problem Explain at least five relational algebraic operators with a suitable example. Note: All the above descriptions should be done by taking at least two examples from ou
Express the subsequent query in SQL assumes which the data is stored within EMPLOYEE table with relevant fields (i) Display name, job, salary, and hire date of employee who are
Draw an entity relationship diagram (ERD) for the following situation: A company has a number of employees. Each employee is identified by an Employee_Id. The company wants to st
How nulls are treated in comparison operator? Along with comparison (relational) operators, the null values are ignored as we cannot derive the relation along with the given op
employee(empid,empname,dept,telno,mobno, add,sssno,tinno,WEdates,WEcomp,WEadd,WEpos,WEres) this is a employee record which is need to be normalize.the WE means work experience
what is stracture of dabms
What is database utility? Database utility is the interface among the ABAP/4 Dictionary and the underlying the SAP system.
Ask question #MinimThe Georgia Tech Library (GTL) has approximately 16,000 members, 100,000 titles, and 250,000 volumes (an average of 2.5 copies per book). About 10 percent of the
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