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’);
