PL/SQL - Relational Operators

Relational operators compare two expressions or values and return a Boolean result. Following table shows all the relational operators supported by PL/SQL. Let us assume variable A holds 10 and variable B holds 20, then −

Operator	Description	Example
=	Checks if the values of two operands are equal or not, if yes then condition becomes true.	(A = B) is not true.
!= <> ~=	Checks if the values of two operands are equal or not, if values are not equal then condition becomes true.	(A != B) is true.
>	Checks if the value of left operand is greater than the value of right operand, if yes then condition becomes true.	(A > B) is not true.
<	Checks if the value of left operand is less than the value of right operand, if yes then condition becomes true.	(A < B) is true.
>=	Checks if the value of left operand is greater than or equal to the value of right operand, if yes then condition becomes true.	(A >= B) is not true.
<=	Checks if the value of left operand is less than or equal to the value of right operand, if yes then condition becomes true.	(A <= B) is true

Example

DECLARE 
   a number (2) := 21; 
   b number (2) := 10; 
BEGIN 
   IF (a = b) then 
      dbms_output.put_line('Line 1 - a is equal to b'); 
   ELSE 
      dbms_output.put_line('Line 1 - a is not equal to b'); 
   END IF;  
   IF (a < b) then 
      dbms_output.put_line('Line 2 - a is less than b'); 
   ELSE 
      dbms_output.put_line('Line 2 - a is not less than b'); 
   END IF; 
    
   IF ( a > b ) THEN 
      dbms_output.put_line('Line 3 - a is greater than b'); 
   ELSE 
      dbms_output.put_line('Line 3 - a is not greater than b'); 
   END IF;  
   -- Lets change value of a and b 
   a := 5; 
   b := 20; 
   IF ( a <= b ) THEN 
      dbms_output.put_line('Line 4 - a is either equal or less than b'); 
   END IF; 
   IF ( b >= a ) THEN 
      dbms_output.put_line('Line 5 - b is either equal or greater than a'); 
   END IF;
   IF ( a <> b ) THEN 
      dbms_output.put_line('Line 6 - a is not equal to b'); 
   ELSE 
      dbms_output.put_line('Line 6 - a is equal to b'); 
   END IF;  
END; 
/

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

Line 1 - a is not equal to b 
Line 2 - a is not less than b 
Line 3 - a is greater than b 
Line 4 - a is either equal or less than b 
Line 5 - b is either equal or greater than a 
Line 6 - a is not equal to b  

PL/SQL procedure successfully completed

plsql_operators.htm