PL/SQL - Basic Syntax

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Following table shows the Logical operators supported by PL/SQL. All these operators work on Boolean operands and produces Boolean results. Assume variable A holds true and variable B holds false, then:

OperatorDescriptionExample
and Called logical AND operator. If both the operands are true then condition becomes true. (A and B) is false.
orCalled logical OR Operator. If any of the two operands is true then condition becomes true. (A or B) is true.
notCalled logical NOT Operator. Used to reverse the logical state of its operand. If a condition is true then Logical NOT operator will make it false. not (A and B) is true.

Example:

DECLARE
   a boolean := true;
   b boolean := false;
BEGIN
   IF (a AND b) THEN
      dbms_output.put_line('Line 1 - Condition is true');
   END IF;
   IF (a OR b) THEN
      dbms_output.put_line('Line 2 - Condition is true');
   END IF;
   IF (NOT a) THEN
      dbms_output.put_line('Line 3 - a is not true');
   ELSE
      dbms_output.put_line('Line 3 - a is true');
   END IF;
   IF (NOT b) THEN
      dbms_output.put_line('Line 4 - b is not true');
   ELSE
      dbms_output.put_line('Line 4 - b is true');
   END IF;
END;
/

When the above code is executed at SQL prompt, it produces the following result:

Line 2 - Condition is true
Line 3 - a is true
Line 4 - b is not true

PL/SQL procedure successfully completed.


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