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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));
write-set(T): Each data items that are written by a transaction T
Explain the Natural join Natural join is a binary operator which is written as (R* S) in which R and S are relations. The effect of the natural join is the set of all combinati
What are the different integrity constraints in RDBMS? The various integrity constraints in RDBMS are as: Primary Key: primary key is a grouping of one or more attributes
project on dbms
What is the max. no. Of structures that can be included in a table or structure. Nine.
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Explain the ACID properties of a transaction Ans: ACID properties are a significant concept for databases. The ACID stands for Atomicity, Consistency, Isolation, and Durability
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