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a domain is a set of permissible values that can be given to an attribute so each attribute in a table has a definite domain values to these
before we talk about the relational model in more detail let us first define some very basic terms used in this modeltupleevery row in a table shows
a model in database system mostly defines the organisation of data or structure and a set of operations on that data relational model is a easy model
in the first unit of this block you have been given with the details of the database management system its structure advantages etc this unit is an
record based logical models use records as the key data representation componentsexamplesrelational model it shows data as well as relationship
object-based models use objects as key data representation componentsexamples- entity-relationship model it is a collection of real world
after going by the database architecture let us now dwell on an important query how is the data organised in a database there are a lot of basic
these permit the user to unload a database or parts of a database and reload the data on the similar machine or on another machine in a dissimilar
these are designed to reduce the effects of a database failure and make sure a database is restored to a consistent state if a failure does arise
these are interactive interfaces graphical that hide the difficulty of the dbms and query language behind an intuitive simple to understand and
command line interfaces these are interactive interfaces character-based that let you use the complete power and functionality of the dbms query
there are three main sources of utilities and applications for a dbmsa vendor applications and utilities are given for working with or maintaining
at its most essential level the dbms architecture can be divide into two parts the back end and the front endthe back end is responsible for managing
an ideal data dictionary should have everything a dba wants to know about the database1 conceptual external and internal database
the database administrator dba uses the data dictionary in each phase of a database life cycle beginning from the data gathering phase to the design
the indices are accumulated in the index files the data is accumulated in the data files indices give fast access to data items for example a book
write a query that uses the union operator1 use the software experts database to a display the first and the last name of all consultants who
a customer places orders for parts and belongs to a particular industry group an individual order is taken by a particular sales representative on a
database administratorone of the main perpose for having the database management system is to have control of both data or programs accessing that
query processorthe query language processor is responsible for taking query language statements or shifting them from the english-like syntax of the
database managerit is the interface among low-level data queries and application programs databases typically need a large amount of storage space it
file managerfile manager handles the allocation of space on disk storage it starts and maintains the list of structures and indices described in the
ddl compilerthe ddl compiler changes the data definition statements such as create table in sql into a set of tables having metadata tables these
dml precompilerall the dbms have two basic sets of languages - data definition language ddl that have the set of commands needed to define the format
insulation between conceptual and physical structuresit can be defined as1 the database administrator should be capable to vary the storage