Oracle® TimesTen InMemory Database PL/SQL Packages Reference Release 11.2.1 Part Number E1400001 


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The DBMS_RANDOM package provides a builtin random number generator. DBMS_RANDOM is not intended for cryptography.
This chapter contains the following topics:
Operational notes
DBMS_RANDOM.RANDOM produces integers in [2^^31, 2^^31).
DBMS_RANDOM.VALUE produces numbers in [0,1) with 38 digits of precision.
DBMS_RANDOM can be explicitly initialized, but does not need to be initialized before calling the random number generator. It will automatically initialize with the date, user ID, and process ID if no explicit initialization is performed.
If this package is seeded twice with the same seed, then accessed in the same way, it will produce the same results in both cases.
In some cases, such as when testing, you may want the sequence of random numbers to be the same on every run. In that case, you seed the generator with a constant value by calling one of the overloads of DBMS_RANDOM.SEED. To produce different output for every run, simply omit the call to "Seed" and the system will choose a suitable seed for you.
Table 51 DBMS_RANDOM package subprograms
Subprogram  Description 

Initializes the package with a seed value. 

Returns random numbers in a normal distribution. 

Generates a random number. 

Resets the seed. 

Gets a random string. 

Terminates package. 

This function gets a random number, greater than or equal to 0 and less than 1, with 38 digits to the right of the decimal point (38digit precision), while the overloaded function gets a random Oracle number 
Note:
The INITIALIZE procedure, RANDOM function and the TERMINATE procedure are all obsolete and, while currently supported, are included in this release for legacy reasons only.Note:
Notes on data types:The PLS_INTEGER and BINARY_INTEGER data types are identical. This document uses "BINARY_INTEGER" to indicate data types in reference information (such as for table types, record types, subprogram parameters, or subprogram return values), but may use either in discussion and examples.
The INTEGER and NUMBER(38) data types are also identical. This document uses "INTEGER" throughout.
This procedure initializes the generator (but see the usage notes).
Syntax
DBMS_RANDOM.INITIALIZE ( val IN BINARY_INTEGER);
Pragmas
PRAGMA restrict_references (initialize, WNDS);
Parameters
Table 52 INITIALIZE procedure parameters
Parameter  Description 

val 
The seed number used to generate a random number. 
Usage notes
This procedure is obsolete as it simply calls the SEED procedure.
This function returns random numbers in a standard normal distribution.
Syntax
DBMS_RANDOM.NORMAL RETURN NUMBER;
Pragmas
PRAGMA restrict_references (normal, WNDS);
Return value
This procedure generates and returns a random number.
Syntax
DBMS_RANDOM.RANDOM RETURN binary_integer;
Pragmas
PRAGMA restrict_references (random, WNDS);
Return value
Table 54 RANDOM return value
Parameter  Description 

binary_integer 
A random integer greater or equal to power(2,31) and less than power(2,31). 
This procedure resets the seed.
Syntax
DBMS_RANDOM.SEED ( val IN BINARY_INTEGER); DBMS_RANDOM.SEED ( val IN VARCHAR2);
Pragmas
PRAGMA restrict_references (seed, WNDS);
Parameters
Table 55 SEED procedure parameters
Parameter  Description 

val 
Seed number or string used to generate a random number. 
Usage notes
The seed can be a string up to length 2000.
This function generates and returns a random string.
Syntax
DBMS_RANDOM.STRING opt IN CHAR, len IN NUMBER) RETURN VARCHAR2;
Pragmas
PRAGMA restrict_references (string, WNDS);
Parameters
Table 56 STRING function parameters
Parameter  Description 

opt 
Specifies what the returning string looks like:
Otherwise the returning string is in uppercase alpha characters. 
len 
The length of the returning string. 
Return value
When you are finished with the package, call the TERMINATE procedure (but see Usage notes)
Syntax
DBMS_RANDOM.TERMINATE;
Usage notes
This procedure performs no function and, although it is currently supported, it is obsolete and should not be used.
The basic function gets a random number, greater than or equal to 0 and less than 1, with 38 digits to the right of the decimal (38digit precision). Alternatively, you can get a random Oracle number x
, where x
is greater than or equal to low
and less than high
.
Syntax
DBMS_RANDOM.VALUE RETURN NUMBER; DBMS_RANDOM.VALUE( low IN NUMBER, high IN NUMBER) RETURN NUMBER;
Parameters
Table 58 VALUE function parameters
Parameter  Description 

low 
The lowest number in a range from which to generate a random number. The number generated may be equal to 
high 
The highest number below which to generate a random number. The number generated will be less than 
Return value