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Video Title: Data Dictionary
Description: Data Dictionary
Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm
Lecture By: Mr. Arnab Chakraborty, Tutorials Point India Private Limited
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In this session, we are going to discuss
Data Dictionary.

Data dictionary is actually data about
data.

It deals with what is the definition of
the data, what is the origin of the data,

how the data will get used, what is the
data format, what are the data domain,

data constraints, all these things will be
mapped onto the data dictionary.

And data dictionary
is actually depicting the

full database
of the system in one documentation.

And it resolves all sorts of data related
anomalies.

So, let us go into the details of this
data dictionary.

So, data dictionary is the centralized
collection of information about data and

it stores meaning and the origin of data,
its relationship with other data,

data format, usage, any kind of data
constraints, respective domain, etcetera.

And data dictionary has a rigorous
definition of all names in order to

facilitate user and software designers.

Data dictionary is often referenced at
metadata that is data about data repository.

It is created along with the DFD model of
software program and is expected to be

updated whenever DFD is changed on or the
DFD is getting updated.

So, it resolves all sorts of ambiguities
whenever the DFDs are getting changed,

the respective data dictionary will have
the respective updates to resolve.

So, requirement of data dictionary.

The data is referenced by data dictionary
while designing and implementing software.

Data dictionary removes any chances of
ambiguity.

It helps keeping work of programmers and
designers synchronized while using same

object name, object reference everywhere
in the program.

So, always it will try to resolve all
sorts of anomalies.

And whenever designers and developers are
trying to access a certain data object,

so there should not be any ambiguity
because they will be using the data object

in multiple different places of the
software in the software process.

So, that is why all sorts
of ambiguities will

be resolved through
these data dictionaries.

So, data dictionary provides a way of
documentation

for the complete database
system in one place.

So, validation of DFD is carried out using
data dictionary.

So, what are the contents?

We are having data
flow, data structure, data

elements, data stores
and data processing.

Data flow is described by means of DFDs as
studied earlier in the earlier videos and

represented in algebraic form which will
be described next.

So, now let us see that how this algebraic
form can be written.

So, here we are having multiple different
symbols and respective meaning is there.

Equal to stands for composed of.

So, this bracket is denoting the
repetition, this brackets are denoting the

optional, this plus is denoting the and
and this slash is denoting this of.

So, let me discuss
that one and this slash

should be
enclosed within these third brackets.

So, now here you can
see that here we are having this address

is equal to this
is our house number plus denoting the OR.

And here we are having this street oblique
area.

So, here you
can find that this street oblique area

means OR and
here you see here we having this one.

The first brackets are there enclosing
means optional.

So, this section is optional city,
then and, then state.

In this way, this address will be
composed.

In case of course ID, we are having
this course number

and course name
and course level and course grades.

So, in this way, this respective course ID
can be formed.

So, this is the algebraic expressions.

So, data elements consists of name and
descriptions of data and control items,

intervals or external data stores etcetera
with the following details.

So, what are the details?

We are having this primary name,
the secondary name will be used for alias

and then use case, how and where to use
this particular data, content description,

notations etcetera.

We are having the
supplemented information that

is a preset
values and the constraints etcetera.

So, these are the different
data elements and

we are giving them
in the respective details.

So, now we are going to discuss our data
store.

It stores the information from where the
data enters into the system and exits out

from the system.

So, that is the store.

So, where the data will be coming and data
will be going out.

The data store may include what are the
components of data store?

That is the file internal to the software,
external to the software but on The same

machine external to the software and system
located on to some different machine.

So, there is a files.

We are going to have the tables,
naming conventions, indexing property.

We are going to have this data processing.

And here we are having there are two types
of data processing.

One is a logical as user sees it and another
one is a physical as software sees it.

So, in this way we are having multiple
different components in our data store.

So, they are files, tables and data
processing.

So, in this video we have discussed what
is a dictionary, what is a data dictionary

and what are its different components and
how this data dictionary is playing a very

vital role in our software development
process.

Thanks for watching this video.