Oracle Random number _oracle

Using Oracle's Dbms_random package combined with rownum to achieve, for example, under random access to 499 households:
SELECT * FROM
(SELECT * from Busi.t_ar_userinfo ORDER by Dbms_random.value)
where RowNum < 500;

References to Dbms_random, links to: http://www.psoug.org/reference/dbms_random.html

Deprecated. Using the methods in the Dbms_crypto built-in package, this package has not been recommended for use

Attached, dbms_random several parameters of the introduction:
function value return number, which returns the random numbers between [0,1], with a precision of 38 digits (Gets a random number, greater than or equal to 0 and less than 1, with Decimal digits)
function value (low in Numvber,high in number) returns, returning a random count between [Low,high]
function normal return Number,return random numbers in a standard normal distribution, returns a group of the normal distribution, the standard deviation is 1, the expected value is 0, and the return values are 68% Between +1 and-1, 95% is between +2 and-2, and 99% is between +3 and 3.
function random return Binary_integer, (Generate random Numeric Values),
function string (opt char,length number) return VARCHAR2 (the maximum is 60) returns a string of the specified length (Create Random Strings), opt seed V Alues:
' A ', ' a ' &n

Q: I work the problem: The supervisor let me for an event to randomly remove some qualified email or mobile phone number users to issue award-winning notice or other information, our company's Oracle 9i How to achieve this?
A: You can use ORACLE to generate random numbers of Pl/sql, directory file name in:/oracle_home/rdbms/admin/dbmsrand.sql.
To compile under the SYS user before using:
Sql>@/oracle_home/rdbms/admin/dbmsrand.sql
It actually generates a DBMS_RANDOM package under the SYS user, generates a public synonym, and authorizes all database users to have permission to execute.
Using the Dbms_random package, the method of taking random data out:
1. First create a unique growth serial number tmp_id
Create sequence tmp_id increment by 1-start with 1 maxvalue 9999999 nocycle;
2. Then create a temporary table tmp_1 to take out all the records that meet the conditions of this activity.
CREATE TABLE Tmp_1 as select Tmp_id.nextval as Id,email,mobileno from table name where condition;
Find the largest ID number:
Select Max (id) from tmp_1;
assumed to be 5000
3. Set a seed to generate random numbers
Execute Dbms_random.seed (12345678);
Or
Execute Dbms_random.seed (to_char (sysdate, ' mm-dd-yyyy HH24:MI:SS '));
4. Call random number generation function Dbms_random.value generate temporary table tmp_2
Suppose you randomly take 200
CREATE TABLE tmp_2 as Select Trunc (Dbms_random.value (1,5000)) as ID from tmp_1 where rownum<201;
[Description: Dbms_random.value (1,5000) is a random number between 1 and 5000, with decimals,
The trunc function takes a random number rounding to correspond to the integer ID field of a temporary table.
Note: If the tmp_1 record is more (100,000 or more), you can also find a table of about 200 rows (if it is tmp_3) to generate tmp_2
CREATE TABLE tmp_2 as Select Trunc (Dbms_random.value (1,5000)) as ID from Tmp_3 where rownum<201; ]
5. Tmp_1 and tmp_2 associated with the acquisition of eligible 200 users
Select T1.mobileno,t1.email from Tmp_1 t1,tmp_2 T2 where t1.id=t2.id;
[Note: If the tmp_1 record is more than 100,000, you need to index the ID field.] ]
You can also output to a text file:
Set pagesize 300;
Spool/tmp/200.txt;
Select T1.mobileno,t1.email from Tmp_1 t1,tmp_2 T2 where t1.id=t2.id order by T1.mobileno;
Spool off;
6. After use, delete temporary table tmp_1, tmp_2 and serial number tmp_id.