Random Display of Query Results (no repeats)

[image_maker1]

First of all, I am a ColdFusion novice, so please forgive me if the answer to this is either blantantly obvious or totally impossible. Here is my problem.

I am querying a database with several hundred records. The query will return on average between 10 - 15 records. I then want to display 2 of these records on a random basis. I do have this much working. The only problem is that every so often, the 2 records that are displayed are the same record. I need to avoid this outcome. The 2 records should always be different.

Here is a simplified version of my code:

<CFQUERY name="queryname" datasource="datasourcename">
SELECT * FROM Residential
WHERE ListingOfficeName = 'Widner Realty'
</CFQUERY>

<cfset randRecordsList = ''>
<cfloop from="1" to="2" index="i">
<cfset randVal = randRange(1,queryname.recordCount)>
<cfset randRecordsList = listAppend(randRecordsList , randVal)>
</cfloop>

<cfloop list="#randRecordsList#" index="i">
<cfoutput>
#queryName.FieldName1 #
#queryName.FieldName2#
#queryName.FieldName3 #<br>
</cfoutput>
</cfloop>

Any help would be appreciated. Thanks in advance.

[Dan_Bracuk · Accepted solution]

Here is the general idea. You can look after the specifics.

// generate list of numbers.
maxnum = 15;
numlist = "";
for (i = 1; i lte maxnum; i = i + 1)
numlist = listappend(numlist, i);

// randomnums will have the two random numbers
RandomNums = "";
x = true;
while (x is true) {
ThisNum = RandRange(1, maxNum);
if (ListFind(RandomNums, ThisNum) is false)
RandomNums = ListAppend(RandomNums, ThisNum);

if (ListLen(RandomNums) is 2)
x = false;
}

[image_maker1]

Thanks for the help. I got it working using your suggestions.

[Dan_Bracuk]

Oh, by the way, make sure you have at least two records before trying that code or you will end up in an infinite loop.