Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Explain entity integrity and referential integrity rules within relational model. Show how these are realized in SQL?
Entity Integrity Rule - No primary key value could be null.
Referential Integrity Rule - In referential integrity, it is ensured in which a value which appears in one relation for a given set of attributes also appears for a certain set of attributes within another relation.
In SQL, entity integrity and referential integrity rules are implemented as constraints on the relation known as primary key constraint or reference key constraint corresponding. These constraints can be specified along with relation at the time of creation of the relations or after the creation of the relations through altering the definition of the relations. For instance:
CREATE TABLE DEPT
(DEPTNO NUMBER PRIMARY KEY,
DNAME VARCHAR2(15));
CREATE TABLE EMP
(EMPNO NUMBER PRIMARY KEY,
20
ENAME VARCHAR2(15),
JOB VARCHAR2(10),
DEPTNO NUMBER REFERENCES DEPT(DEPTNO));
Describe queries with complex types? The present extension of the SQL query language deal with the complex type Let us start with the simple example: Find the title and t
random file orgnization
Explain the Cascadeless Schedule A cascadeless schedule is one in which for every pair of transactions Ti and Tj like that Tj reads a data item before written by Ti, the commit
Explain the Exec statement in SQL Ans: Exec statement has the structure EXEC SQL END-EXEC Embeded SQl statements are of a form identical to non embedded SQL statem
Define the terms entity, attribute, role and relationship between the entities, giving examples for each of them. Ans: Entity: An entity is a "thing" or "object" in th
Single Valued Normalisation Codd in the year 1972 formed three normal forms (1NF, 2NF, and 3NF). These were based on functional dependencies between the attributes of a relati
Explain the following functions of Oracle with suitable examples: (i) To_Char( ) (ii) Count( ) (iii) Trim( ) (iv) Length( ) Ans: (i) To_char( ): The TO_CHAR function conver
Attributes having a one value for a particular entity. For instance, Age is a single valued attribute of a student entity. Attributes that have more than single values
Derived horizontal fragmentation: Some applications may include a join of two or more relations. If the relations are stored at dissimilar locations, there may be a major overhead
Make SQL statements for the following scenarios. Your response should contain SQL statement, output and any other assumptions you have made to arrive at the answer. For Colorado cu
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd