The first version of VALUE returns a random number that is greater than or equal to 0 and less than 1. The second version of VALUE returns a random number that is greater than or equal to LOW and less than HIGH. Here is an example of their usage: SQL> select dbms_random.value, dbms_random.value(55,100) 2 from dual; VALUE DBMS_RANDOM.VALUE(55,100) --------------- ----------------------------- .782821936 79.6367038
The DBMS_RANDOM package provides a built-in random number generator. It is faster than generators written in PL/SQL because it calls Oracle's internal random number generator. RequirementsDBMS_RANDOM must be initialized prior to calling the random number generator. The generator produces 8 digit integers. If the initialization subprogram is not called, then the package raises an exception. Summary of SubprogramsSubprogram Description INITIALIZE procedure Initializes the package with a seed value. SEED procedure Resets the seed. RANDOM function Gets the random number. TERMINATE procedure Closes the package. TTo use the package, first call the initialize subprogram with the seed to use. SyntaxDBMS_RANDOM.INITIALIZE ( seed IN BINARY_INTEGER);Note: Use a seed that is sufficiently large, more than 5 digits. A single digit might not return sufficiently random numbers. Parameter Description seed Seed number used to generate a random number. This function gets the random number. SyntaxDBMS_RANDOM.RANDOM RETURN BINARY_INTEGER;Parameters: None. Examplemy_random_number := Random;
dbms_random.value(55,100)
2 from dual; VALUE DBMS_RANDOM.VALUE(55,100)
--------------- -----------------------------
.782821936 79.6367038
TTo use the package, first call the initialize subprogram with the seed to use. SyntaxDBMS_RANDOM.INITIALIZE (
seed IN BINARY_INTEGER);Note: Use a seed that is sufficiently large, more than 5 digits. A single digit might not return sufficiently random numbers. Parameter Description seed Seed number used to generate a random number.
This function gets the random number. SyntaxDBMS_RANDOM.RANDOM
RETURN BINARY_INTEGER;Parameters: None. Examplemy_random_number := Random;
或者在dba_studio中到sys用户拥有的包中看原码,上面的注释写的很清楚,还有参数的使用和意义。