RPGLESQL - random records from large file

A large file,say a million records in which there are about 12,000 records with a "W" in Field20.  I want 10 random records from the 12000.  I can't figure out how to write the WHERE clause so that only records from the 12,000 will be included .

Here's what I use for random hits on the big file:

       exec sql select rand(MICROSECOND(CURRENT_TIMESTAMP)) into :wField5
           from SYSIBM/SYSDUMMY1;
       wSeed = wField5 * 10000;
       // ---------------------------------------------------------------------
       // Get 10 random numbers
       clear wCount;
       wNdx = 0;
       dow wNdx < 10 and wCount < 1200;  // (if we can't get 10 in 1200, bail)
         wCount += 1;
         exec sql select rand(:wSeed) into :wField5
           from SYSIBM/SYSDUMMY1;
         wSeed = wField5 * 10000;
         exec sql select FIELD1 into :wField1
                    from FILE01
                    where rrn(FILE01) = :wSeed;

...

"where rrn(FILE01) = :wSeed and FIELD20 = 'W';" seems easy but somehow wrong.