Operators
“AND”, “OR”
Sometime we need to combine two or more TSQL statement based on
some conditions, that we can achieve using Conditional
operator, Boolean “AND operator” and “OR operator”
Boolean Operator: AND (&), OR
(||)
Conditional Operator:-
1.
GREATER THEN EQUAL (>=)
X>Y;
2.
LESS THEN EQUAL ( <=)
Y<X;
3.
EQUAL ( ==)
X=Z;
4.
GREATER THEN ( >)
X>Y;
5.
LESS THEN (<)
Y<Z;
6.
NOT EQUAL TO ( <>)
Y<>Z;
The AND operator can be used to
join two or more conditions in the WHERE clause. Both sides of the AND
condition must be true in order for the condition to be met and for those rows
to be displayed.
For example:
SELECT
COLUMN1, COUNT (COLUMN2) FROM TABLENAME WHERE "CONDITION1" AND
"CONDITION2";
The OR operator can be used to
join two or more conditions in the WHERE clause. However, either side
of the OR operator can be true and the condition will be encountered - hence,
the rows will be displayed. With the OR operator, either side can be true or
both sides can be true.
For example:
SELECT
EMPLOYEEID, FIRSTNAME, LASTNAME, TITLE, SALARY FROM EMPLOYEE WHERE BASIC_PAY
>= 15000.00 AND TITLE = 'AVP';
This statement will select the EMPLOYEEID, FIRSTNAME,
LASTNAME, TITLE, SALARY from the employee table where the BASIC pay is greater than or
equal to 15000 and the title is equal to AVP. Both of these conditions must be
true in order for the rows to be returned in the query. If either is false,
then it will not be displayed.
Although they are not required,
you can use parenthesis around your conditional expressions to make it easier
to read:
For example:
SELECT
EMPLOYEEID, FIRSTNAME, LASTNAME, TITLE, SALARY FROM EMPLOYEE WHERE (BASIC_PAY
>= 15000.00) AND (TITLE = 'AVP');
Another
statement get the result set basic_pay>15000 and title can be AVP or VP.
For example:
SELECT
EMPLOYEEID, FIRSTNAME, LASTNAME, TITLE, SALARY FROM EMPLOYEE WHERE (BASIC_PAY
>= 15000.00) AND (TITLE = 'AVP' OR TITLE=’VP’);
