Comparison Operators (Transact-SQL)

Where clause must have one condition statement in Select statement.
To restrict depending upon condition min requirement is an operator.

1. Relation Operator
2. Logical Operator
3. Arithmetic Operator

1. Relation Operator :

Operator	Times of use
= (Equals)	Equal to
> (Greater Than)	Greater than
< (Less Than)	Less than
>= (Greater Than or Equal To)	Greater than or equal to
<= (Less Than or Equal To)	Less than or equal to
!= (Not Equal To)	Not Equal To
<> (Not Equal To)	Not equal to (not ISO standard)
!> (Not Greater Than)	Not greater than (not ISO standard)
!< (Not Less Than)	Not less than (not ISO standard)

Ex:
SELECT * FROM employee
where salary > 20000

SELECT * FROM employee

where salary !< 20000 

2. Logical Operator:

Operator	Times of use
OR	The row to be selected at least one of the conditions must be true.
AND	A row to be selected all the specified conditions must be true.
NOT	A row to be selected the specified condition must be false.

3. Arithmetic Operator :

Operator	Times of use
+ (Add)	Addition
- (Subtract)	Subtraction
* (Multiply)	Division
% (Modulo)	Returns the integer remainder of a division.