DBMS_RANDOM

The DBMS_RANDOM package provides a number of methods to generate random values. The procedures and functions available in the DBMS_RANDOM package are listed in the following table.

Function/Procedure	Return Type	Description
INITIALIZE(val)	n/a	Initializes the DBMS_RANDOM package with the specified seed value. Deprecated, but supported for backward compatibility.
NORMAL()	NUMBER	Returns a random NUMBER.
RANDOM	INTEGER	Returns a random INTEGER with a value greater than or equal to -2^31 and less than 2^31. Deprecated, but supported for backward compatibility
SEED(val)	n/a	Resets the seed with the specified value.
SEED(val)	n/a	Resets the seed with the specified value.
STRING(opt, len)	VARCHAR2	Returns a random string.
TERMINATE	n/a	TERMINATE has no effect. Deprecated, but supported for backward compatibility.
VALUE	NUMBER	Returns a random number with a value greater than or equal to 0 and less than 1, with 38 digit precision.
VALUE(low, high)	NUMBER	Returns a random number with a value greater than or equal to low and less than high.

INITIALIZE

The INITIALIZE procedure initializes the DBMS_RANDOM package with a seed value. The signature is:

INITIALIZE(<val> IN INTEGER)

This procedure should be considered deprecated; it is included for backward compatibility only.

Parameters

val

val is the seed value used by the DBMS_RANDOM package algorithm.

Example

The following code snippet demonstrates a call to the INITIALIZE procedure that initializes the DBMS_RANDOM package with the seed value, 6475.

DBMS_RANDOM.INITIALIZE(6475);

NORMAL

The NORMAL function returns a random number of type NUMBER. The signature is:

<result> NUMBER NORMAL()

Parameters

result

result is a random value of type NUMBER.

Example

The following code snippet demonstrates a call to the NORMAL function:

x:= DBMS_RANDOM.NORMAL();

RANDOM

The RANDOM function returns a random INTEGER value that is greater than or equal to -2 ^31 and less than 2 ^31. The signature is:

<result> INTEGER RANDOM()

This function should be considered deprecated; it is included for backward compatibility only.

Parameters

result

result is a random value of type INTEGER.

Example

The following code snippet demonstrates a call to the RANDOM function. The call returns a random number:

x := DBMS_RANDOM.RANDOM();

SEED

The first form of the SEED procedure resets the seed value for the DBMS_RANDOM package with an INTEGER value. The SEED procedure is available in two forms; the signature of the first form is:

SEED(<val> IN INTEGER)

Parameters

val

val is the seed value used by the DBMS_RANDOM package algorithm.

Example

The following code snippet demonstrates a call to the SEED procedure; the call sets the seed value at 8495.

DBMS_RANDOM.SEED(8495);

SEED

The second form of the SEED procedure resets the seed value for the DBMS_RANDOM package with a string value. The SEED procedure is available in two forms; the signature of the second form is:

SEED(<val> IN VARCHAR2)

Parameters

val

val is the seed value used by the DBMS_RANDOM package algorithm.

Example

The following code snippet demonstrates a call to the SEED procedure; the call sets the seed value to abc123.

DBMS_RANDOM.SEED('abc123');

STRING

The STRING function returns a random VARCHAR2 string in a user-specified format. The signature of the STRING function is:

<result> VARCHAR2 STRING(<opt> IN CHAR, <len> IN NUMBER)

Parameters

opt

Formatting option for the returned string. option may be:

Option	Specifies Formatting Option
u or U	Uppercase alpha string
l or L	Lowercase alpha string
a or A	Mixed case string
x or X	Uppercase alpha-numeric string
p or P	Any printable characters

len

The length of the returned string.

result

result is a random value of type VARCHAR2.

Example

The following code snippet demonstrates a call to the STRING function; the call returns a random alpha-numeric character string that is 10 characters long.

x := DBMS_RANDOM.STRING('X', 10);

TERMINATE

The TERMINATE procedure has no effect. The signature is:

TERMINATE

The TERMINATE procedure should be considered deprecated; the procedure is supported for compatibility only.

VALUE

The VALUE function returns a random NUMBER that is greater than or equal to 0, and less than 1, with 38 digit precision. The VALUE function has two forms; the signature of the first form is:

<result> NUMBER VALUE()

Parameters

result

result is a random value of type NUMBER.

Example

The following code snippet demonstrates a call to the VALUE function. The call returns a random NUMBER:

x := DBMS_RANDOM.VALUE();

VALUE

The VALUE function returns a random NUMBER with a value that is between user-specified boundaries. The VALUE function has two forms; the signature of the second form is:

<result> NUMBER VALUE(<low> IN NUMBER, <high> IN NUMBER)

Parameters

low

low specifies the lower boundary for the random value. The random value may be equal to low.

high

high specifies the upper boundary for the random value; the random value will be less than high.

result

result is a random value of type NUMBER.

Example

The following code snippet demonstrates a call to the VALUE function. The call returns a random NUMBER with a value that is greater than or equal to 1 and less than 100:

x := DBMS_RANDOM.VALUE(1, 100);