PL/SQL - 關係運算符

關係運算符比較兩個表示式或值並返回布林結果。下表顯示了 PL/SQL 支援的所有關係運算符。假設變數 A持有 10 且變數 B持有 20，則 -

示例

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; 
/ 

當以上程式碼在 SQL 提示符下執行時，會產生以下結果 -

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