What does every 15th row mean? Would only storing every 15th sample be more appropriate? On 19 Jan 2011 16:22, "Stephens, Chris" <Chris.Stephens@xxxxxxx> wrote: 188.8.131.52 on Linux 5 We have a lab instrument recording information every 2 seconds into a table. The scientists pull that data into excel for analysis (I hope to look at this excel spreadsheet in the very near future now that I’ve read chapter 9 of Pro Oracle SQL). They are requesting a view that picks out every 15th row of data going back 30 days. Can anyone think of a more efficient way to do it than this: SELECT x.col, x.t_stamp FROM ( SELECT col, t_stamp rownum rn FROM t WHERE t_stamp >= TRUNC( SYSDATE - 30 )) x WHERE MOD( x.rn, 15 ) = 0; It feels like there should be a better way to do it. chris CONFIDENTIALITY NOTICE: This message is intended for the use of the individual or entity to which it is addressed and may contain information that is privileged, confidential and exempt from disclosure under applicable law. If the reader of this message is not the intended recipient or the employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by email reply.