PLSQL generate random integer

Question

In Oracle Sql developer 11g, how do I generate a random integer and assign it to a variable? This is what I've tried so far:

S_TB := SELECT dbms_random.value(1,10) num FROM dual;

With this code I got error:

S_TB := SELECT dbms_random.value(1,10) num FROM dual
Error report -
Unknown Command

What is the proper way to solve my issue?

Answer 1

Variables require PL/SQL; it's not clear from your question whether your code is a proper PL/SQL block. In PL/SQL variables are populated from queries using the INTO syntax rather than the assignment syntax you're using.

declare
    txt varchar2(128);
    n pls_integer;
begin
    --  this is how to assign a literal
    txt := 'your message here';

    --  how to assign the output from a query
    SELECT dbms_random.value(1,10) num 
    into n
    FROM dual;

end;

Although, you don't need to use the query syntax. This is valid, and better practice:

declare
    n pls_integer;
begin
    n := dbms_random.value(1,10);
end; 

Answer 2

Alternatively, You can create a function for generating random numbers. This can be used in anywhere in the code.

    create or replace function RANDOM
    return number 
    is 
    a number ; 
    begin
    select round(dbms_random.value(1,10)) rnum
    into a 
    from dual;
    return a  ;
    end;
    /

OUTPUT:

Function created.

SQL> select Random from dual;

RANDOM

     6                                                                                                                  

SQL> select Random from dual;

RANDOM

     9                                                                                                                  

Answer 3

If you want to get a random number of n digits you can do this

CREATE OR REPLACE FUNCTION NUM_RANDOM(N IN NUMBER)
RETURN NUMBER 
AS 
BEGIN
    RETURN TRUNC (DBMS_RANDOM.VALUE(POWER(10, N - 1), POWER(10, N) - 1));
END NUM_RANDOM;

Answer 4

For a set of consecutive integers randomly distributed uniformly (in the example below between 1 and 10), I suggest:

select round(dbms_random.value(0.5,10.49999999999),0) from dual

Otherwise I'll unintentionally restrict the first and last number in the set to half the probability of being chosen as the rest of the set.

Answer 5

Integers:

select dbms_random.random from dual

Positive integers:

select abs(dbms_random.random) from dual

Answer 6

DECLARE
l_check Integer:=1;
BEGIN
    WHILE l_check < 5 LOOP
        l_check := DBMS_RANDOM.VALUE(1,10);
        DBMS_OUTPUT.PUT_LINE(l_check);
    END LOOP;
END;

-- DBMS_RANDOM.VALUE Gives the random value within the range.