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!
In a relation, tuples are not inserted in any definite order. Ordering of tuples is not defined as a part of a relation definition. Though, records may be structured later according to some attribute value in the storage systems. For instance, records in PERSON table may be structured according to PERSON_ID. Such organisation or data depends on the requirement of the underlying database application. Though, for the purpose of display we may get them displayed in the sorted order of age. The following table is sorted by age. It is also worth states here that relational model does not permit duplicate tuples
PERSON
PERSON_ID NAME AGE ADDRESS
2 Sharad Gupta 33 Pocket 2, Mayur Vihar.
1 Sanjay Prasad 35 b-4,Modi Nagar
3 Vibhu Datt 36 c-2, New Delhi
Super Keys, Candidate Keys and Primary Keys for the Relations
As discussed in the last section ordering of relations does not matter and all tuples in a relation are unique. Though, can we uniquely recognize a tuple in a relation? Let us talk about the concepts of keys that are primarily used for the purpose as above.
read-set(T) : Each data items that are read by a transaction T Timestamps : for all transaction T, the start-time and the end time are reserved for all the three phases.
Give the general form of SQL query? Select A1, A2............., An From R1, R2..............., Rm Where P
Q. State the Technique for converting a state diagram to code. i) Identify the major control path. Starting with first state, find the path from diagram that corresponds
Mappings between Levels and Data Independence The 3 levels of abstraction in the database do not exist separately of each other. There must be some correspondence, or mapping
What are the authentication modes in SQL Server? How can it be changed? Windows mode and Mixed Mode - SQL and Windows. To alter authentication mode in SQL Server click Start, P
DROP TABLE Command: When an existing object is not needed for further use, it is always better to eliminate it from the database. To remove the existing object from the databas
Mixed fragmentation: Sometimes, horizontal fragmentation or vertical fragmentation of a database schema by itself is insufficient to sufficiently distribute the data for some appli
Define the terms i) DDL ii) DML DDL: Data base schema is particular by a set of definitions expressed by a special language known as a data definition language. DML: A data
What are stored and derived attributes? Stored attributes: The attributes keeps in a data base are known as stored attributes. Derived attributes: The attributes that are de
Eliminate Redundant Data In the "Database Relation" above, the primary key is made up of the D-ID and the Emp-ID. The database-name relies only on the D-ID. The similar databas
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