What is What? Part-I

WHAT IS DATA?

                Constructed Data are given us the Information. These information used for Report, Analysis before that, Data would be stored in certain place. That is, DATABASE.

E.g.:  My name is Ranjith Kumar from Trichy. And I’m Student.

                Here, ‘Ranjith Kumar, Trichy, Student’ are notable Data.

WHAT IS COLUMNS?

                Column holds the same datatype values like an Array in Oops. Here, column is also known as ‘Attribute’. Which is identified by unique name.

Let me explain with above example:

Name		Location		Occupation
Ranjith Kumar		Trichy		Student

Columns are created when table would be created. We can set the Constraints for each column. And tables allows rename, delete and add new column(s).

WHAT IS ROWS?

                Row is nothing but the different type of Data belong to the same object. And row is called as 

‘Tuple’. The specific row is fetched by unique id. 

For example,

1001 (int)

Ranjith Kumar (text)

000 000 0000 (big int)

100000.00  (decimal)

                Here the Id (Unique id), Name, Phone number and Salary are shown as a row. The rows inserted on the table. And we can update and delete a specific row(s).

WHAT IS TABLE?

                Table contains the rows and columns. For both store and display the Data. In Database, we can create more tables. From the Column and Row examples, table looks like:

Id	Name	Phone Number	Salary
1001	Ranjith	000 000 0000	100000
1002	Pugal	111 111 1111	100000

WHAT IS VIEW?

                View is works like an actual table. Because, it is created from table(s) as select query. So, it is called as ‘virtual table’. We can INSERT, UPDATE, DELETE, when view refers a single table.

In other hand, we can say view as a ‘Window’. Through the window, we can see only the certain area. Generally, which is used for security purpose.

Employee Id	Name	Phone Number	Salary
1	Srinath	000 000 0000	200000
2	Mano	111 111 1111	200000
3	Pugal	222 222 2222	100000
4	Ranjith	333 333 3333	100000

If the red border columns (Employee Id, Name, Salary) are created as a ‘view’ from the whole table, then Accountant login is authorised only for these columns (Phone number is unnecessary). At the same time, Admin login is authorised for all columns.

**NOTE**

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