Functional

What IS SQL?

SQL Stands for Structured Query Language.
Structured = In a Processed Way,Proper Methodical Approach
Query = Asking Questions
Language = Mode / Medium of Communication
So SQL = Structured + Query + Language
             = (In a Processed Way, Proper Methodical Approach) + (Asking Questions) + (Mode / Medium of Communication)
After a rearrangement if we try to construct a line it could be:
Mode / Medium of Communication Via Asking Questions

1. Mode / Medium of Asking Questions in a proper methodical approach.
   
   

Out of the above two the option 2 sounds better hence I will choose 2.
So SQL now stands for Mode / Medium of Asking Questions in a proper methodical approach.
Now this brings us to the next question.
Asking Questions . But Questions are asked by some-one (Individual 1) to Some-One (Individual 2)
So in SQL WHO Asks the Question and To WHOM

WHO = Business / Business User / Technical Consultant
WHOM = Database / ERP System / Any system Holding Data / Datawarehouse
So we come to conclusion that via SQL
Business / Business User / Technical Consultant asks questions to Data Storing System (Commonly referred to as Database) in a proper methodical way (following specific syntax)

Graphical Representation

Database Table:

The above data gets stored into the Database in a Structure Called Table and it looks like as shown below :

Database Column

Each Database Table is made up of one or more vertical rows typically referred to as Columns.

In the above example we have following columns

1. Employee No
   
   
2. Employee Name
   
   
3. Position
   
   
4. Department
   
   

SQL Example

Say a Technical Consultant Adam has been asked by CEO of ABC Company to give him the details of all employees . The Output would be fetched via a SQL.

Sql Syntax

So if we want to get the data of all employees we will have a SQL like :

Sql 1 : Get All Data

SELECT * FROM EMPLOYEES; ---------------------------------------------------------------------------- (a)
                OR
SELECT ALL FROM EMPLOYEES;------------------------------------------------------------------------( b )
                OR
SELECT EMPLOYEE_NO,
              EMPLOYEE_NAME,
              POSITION,
              DEPARTMENT
FROM    EMPLOYEES; -------------------------------------------------------------------------------------- ( c )
                    OR
SELECT E.ALL FROM EMPLOYEES E; ------------------------------------------------------------------( d )
                    OR
SELECT E.* FROM EMPLOYEES E ;  ------------------ ( e )
OR
SELECT E.EMPLOYEE_NO as “Employee No”,
E.EMPLOYEE_NAME as “Employee Name”,
E.POSITION                  as “Position”,
E.DEPARTMENT         as “Department”
FROM EMPLOYEES E                                                                ----------------------------------------- ( f )
Note :- Here in ( c ) we have used ‘E’ for ‘Employees’ which is an alias. Like we have Names (Dinesh) and pet-name (Dinu). So we can refer the to the TABLE with either Real Name ( Employees ) or with Pet-Name ( E )

WHERE CLAUSE

Whenever we want to Restrict Data in SQL we need to use where clause. In this example we have 3 department while we are interested to get data for ABC Sales so SQL will be :

SQL 2 : SQL with Where Clause

SELECT * FROM EMPLOYEES WHERE DEPARTMENT = ‘ABC Sales’; ------------------------------------------------------------- (a)

                OR
SELECT ALL FROM EMPLOYEES WHERE DEPARTMENT = ‘ABC Sales’;------------------------------------------------------------( b )
                OR
SELECT EMPLOYEE_NO,
              EMPLOYEE_NAME,
              POSITION,
              DEPARTMENT
FROM    EMPLOYEES
WHERE DEPARTMENT = ‘ABC Sales’; ------------------------------------------------------------------------------------------------------- ( c )
                    OR
SELECT E.ALL FROM EMPLOYEES E WHERE DEPARTMENT = ‘ABC Sales’------------------------------------------------------ ( d )
                    OR
SELECT E.* FROM EMPLOYEES E WHERE E.DEPARTMENT = ‘ABC Sales’ ;  ------------------ ( e )
OR
SELECT E.EMPLOYEE_NO as “Employee No”,
E.EMPLOYEE_NAME as “Employee Name”,
E.POSITION                  as “Position”,
E.DEPARTMENT         as “Department”
FROM EMPLOYEES E     
WHERE E.DEPARTMENT = ‘ABC Sales’                                                           ----------------------------------------- ( f )

Ashish Harbhajanka

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