Keep in Mind That...
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SQL keywords are NOT case sensitive: 'select' is the same as 'SELECT'


Some of The Most Important SQL Commands :
----------------------------------------
SELECT - extracts data from a database
UPDATE - updates data in a database
DELETE - deletes data from a database
INSERT INTO - inserts new data into a database
CREATE DATABASE - creates a new database
ALTER DATABASE - modifies a database
CREATE TABLE - creates a new table
ALTER TABLE - modifies a table
DROP TABLE - deletes a table
CREATE INDEX - creates an index (search key)
DROP INDEX - deletes an index


Displaying Data:-
----------------
=> "SELECT" command is used to display data.
=> we can display all rows & all cols.
=> we can also display specific rows & cols.
=> The SELECT statement is used to select data from a database.
=> The data returned is stored in a result table, called the result-set.

SELECT Syntax :
SELECT column1, column2, ...
FROM table_name;

=> Here, column1, column2, ... are the field names of the table you want to select data from. 
=> If you want to select all the fields available in the table, use the following 
syntax:
SELECT * FROM table_name;


syntax : SELECT column/* FROM <tableName>

	SQL = Language (suppose English)
	queries = sentence(How you comunicate)
	clauses = words (SELECT , FROM)


FROM clause => specifies tablename
SELECT clause => specifies column name



SQL Server 
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use [AdventureWorks2012]

--all
select * from [HumanResources].[Department]

--SHOW ME ALL THE DEPARTMENT NAMES.
SELECT NAME FROM [HumanResources].[Department]


--SHOW ME ALL THE GROUPS
SELECT GROUPNAME FROM [HumanResources].[Department]

--SHOW ME ALL THE DISTINCT GROUPNAME
SELECT DISTINCT GROUPNAME FROM [HumanResources].[Department]

--SHOW ME ALL THE DEPARTMENT NAME WHO ARE A PART OF MANUFACTURING
SELECT NAME,GROUPNAME FROM [HumanResources].[Department]
WHERE GROUPNAME LIKE 'Manufacturing'

--GIVE ME ALL THE EMPLOYEES FROM THE EMPLOYEE TABLE
SELECT * FROM [HumanResources].[Employee]

--GIVE ME A LIST OF ALL EMPLOYEE WHO HAVE A ORGLEVEL = 2
SELECT * FROM [HumanResources].[Employee] WHERE OrganizationLevel = 2

--GIVE ME A LIST OF ALL EMPLOYEES WHO HAVE ORGLEVEL = 2 OR 3
SELECT * FROM [HumanResources].[Employee] WHERE OrganizationLevel IN (2,3)

--GIVE ME A LIST OF EMPLOYEES WHO HAVE A TITLE AS FACILITIES MANAGER
SELECT * FROM [HumanResources].[Employee] WHERE JobTitle LIKE 'Facilities Manager'

--GIVE ME ALL THE EMPLOYEES WHO HAVE THE WORD MANAGER IN THEIR TITLE
SELECT * FROM [HumanResources].[Employee] WHERE JobTitle LIKE '%MANAGER'

--GIVE ME ALL THE EMPLOYEES WHO HAVE THE WORD SALES IN THEIR JOBTITLE
SELECT * FROM [HumanResources].[Employee] WHERE JobTitle LIKE '%SALES%'



operators in sql server:-
-----------------------

Arithmetic operator => + - * / %
Arithmetic operations returns values
10+5 => 15
10-5 =>5
10*5 => 50
10/5 =>2
10%5 =>0

Relational Operators => > >= < <= = <>
Relational values returns True or False.
10>5 => true
10<5 =>false
10=5 =>false
10<>5 => true   (<> not equal to)

Logical operators =>  AND  OR  NOT
=> This operators are also used in other programming languages but the uses symbols to demonstrate logical operators in other languages


Special operators => (only for SQL)
BETWEEN
IN 
LIKE
IS
ANY
ALL
EXISTS
PIVOT


Set Operators => (only for SQL)
UNION
UNION ALL
INTERSECT
EXCEPT


WHERE clause :-
--------------
=> used to get specific row/rows from table based on a condition.

SELECT columns
FROM tablename
WHERE condition


condition :-
-----------

	COLNAME operator VALUE

=> OP must be any relational operator like 
> >= < <= = <>
=> if condition = true row is  selected
=> if condition is false row is not selected

--GIVE ME A LIST OF ALL EMPLOYEE WHO HAVE A ORGLEVEL = 2
SELECT * FROM [HumanResources].[Employee] WHERE OrganizationLevel = 2

syntax : 
 SELECT * FROM tblName WHERE condition
		or
 SELECT colName FROM tblName WHERE  conditon

=> while comparing the condition the datatype should match or else it will through error

=> employees joined after 2011?
--GIVE ME THE LIST OF EMPLOYEES JOINED AFTER 2011
SELECT * FROM HumanResources.Employee WHERE HireDate > '2011-12-31'

=> employees joined before 2011?
--GIVE ME THE LIST OF EMPLOYEES FROM HUMANRESOURCE.EMPLOYEES TABLE WHO JOINED BEFORE 2011
SELECT * FROM HumanResources.Employee WHERE HireDate < '2011-01-01'



Multiple condition/ Compound Condition
---------------------------------------
=> Multiple conditions combined with AND / OR operators is called compound condition.

syntax:
-------
SELECT * FROM tblName WHERE cond1 LOGICAL OPERATOR cond2

Logical AND table:
------------------
COND1  AND  COND2   RESULT
  T           T        T
  T           F        F
  F           T        F
  F           F        F
=> If both condition is T then result will be T


Logical OR table:
------------------
COND1  AND  COND2   RESULT
  T           T        T
  T           F        T
  F           T        T
  F           F        F
=> If atleast 1 condition is T then result will be T