11.16 Random Number Generation

You use the DBMS_RANDOM package to generate random numbers . You set the seed with the SEED function, which is overloaded.

 PROCEDURE seed(val IN BINARY_INTEGER); PROCEDURE seed(val IN VARCHAR2); 

Two methods for setting a seed are:

 dbms_random.seed(123456); dbms_random.seed(TO_CHAR(SYSDATE,'dd-mon-yyyy hh24:mi:ss'); 

The function VALUE generates a 38-digit precision number within the range:

 0.0 <= value < 1.0 

The function definition for a random number is:

 FUNCTION value RETURN NUMBER; 

The following block illustrates the VALUE function.

 DECLARE     N NUMBER; BEGIN     dbms_random.seed(123456);     N := dbms_random.value;     -- N will be a number similar to:     --     -- 0.92531681298113309873787795771931592618 END; 

You can generate random numbers within a range. You call the function VALUE and pass the low and high limits. The function definition is:

 FUNCTION value(low IN NUMBER, high IN NUMBER) RETURN NUMBER; 

The random number returned is within the range:

 low <= value < high 

The following generates 10 random two-digit integer numbers.

 BEGIN     dbms_random.seed        (TO_CHAR(SYSDATE,'dd-mon-yyyy hh24:mi:ss'));     FOR i in 1..10 LOOP         dbms_output.put_line(TRUNC(dbms_random.value(10,100)));     END LOOP; END;