Is there a way to only return a true random sample of data queried via WebFocus.

This message has been edited. Last edited by: <Kathryn Henning>,

You can do that using RECORDLIMIT OR READLIMIT...

thanks
Sashanka

But it isn't a true random sample.

I believe that in computing in general a true random sample is impossible.

Here's an idea for generating a random sample from a set of records, using the RDUNIF random number function:

SET HOLDLIST = PRINTONLY
SET ASNAMES  = ON
-*
-* Set the desired sample size percent.
-SET &SAMPLE_PERCENT = .10 ;
-*
-* Determine the total population size (DENOMINATOR) and related sample size.
TABLE FILE GGSALES
 SUM
  CNT.SEQ_NO/I10 AS 'DENOMINATOR'
  COMPUTE SAMPLE_SIZE/P10 = CNT.SEQ_NO * &SAMPLE_PERCENT ;
 ON TABLE HOLD AS STATS
END
-*
-RUN
-* Read the DENOMINATOR and SAMPLE_SIZE values into variables.
-READFILE STATS
-* Determine the number of digits needed to extract an appropriate sample size.
-SET &TRIM_DENOM  = TRIM('B',&DENOMINATOR,&DENOMINATOR.LENGTH,' ',1,'A&DENOMINATOR.LENGTH');
-SET &DIGITS      = ARGLEN(&TRIM_DENOM.LENGTH,&TRIM_DENOM,'I3');
-SET &SIGNIFICANT = &DIGITS + 1 ;
-SET &MULTIPLIER  = 1 ;
-*
-* Because function RDUNIF creates random numbers between 0 and 1, generate a MULTIPLIER
-* to force the decimal numbers into an appropriate sample size range.  The multiplier
-* is based on the number of digits in the denominator.
-REPEAT :ENDREPEAT1 &DIGITS TIMES
-SET &MULTIPLIER = &MULTIPLIER || '0';
-:ENDREPEAT1
-*
-* Use function RDUNIF to generate a random number for each record.
-* The number of digits and appropriate multiplier are applied.
DEFINE FILE GGSALES
 RANDOM/P&DIGITS WITH SEQ_NO = RDUNIF('D&SIGNIFICANT...&DIGITS') * &MULTIPLIER ;
END
-*
-* Use the sample size calculated above to extract a random set of records from the population.
TABLE FILE GGSALES
PRINT SEQ_NO DOLLARS/D8M
BY LOWEST &SAMPLE_SIZE RANDOM AS 'Random#'
END

Assuming RDUNIF is sufficiently random for your purposes, would this do the trick?

-SET &SAMPLE_PERCENT = .10 ;
TABLE FILE GGSALES
PRINT
COMPUTE RAND/D9.8=RDUNIF(RAND);
SEQ_NO DOLLARS/D8M
WHERE TOTAL RAND LE &SAMPLE_PERCENT
END

sweet

If you have a real big number of records and you want a random selection of let's say 100 records this wont be easy. Unless you know exactly what the key fields are.
Suppose the key field is a sequential number from 1 till X and you know the highest number then you can have webfocus generate a list of 100 random numbers based on the number X.
Then send the request to the database with exactly the numbers you want to get back.
But if the sequence is not contiguous this will result in missing records.
If you would follow Dan's solution you need to download all the data first to webfocus.