Relational operators compare two expressions or values and return a Boolean result. The following table shows all the relational operators supported by PL/SQL. Let us assumeĀ variable AĀ holds 10 andĀ variable BĀ holds 20, then ā
| Operator | Description | Example |
| = | Checks if the values of two operands are equal or not, if yes then the 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 the condition becomes true. | (A != B) is true. |
| > | Checks if the value of the left operand is greater than the value of the right operand, if yes then the condition becomes true. | (A > B) is not true. |
| < | Checks if the value of the left operand is less than the value of the right operand, if yes then the condition becomes true. | (A < B) is true. |
| >= | Checks if the value of the left operand is greater than or equal to the value of the right operand, if yes then the condition becomes true. | (A >= B) is not true. |
| <= | Checks if the value of the left operand is less than or equal to the value of the right operand, if yes then the 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 ā
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
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