On 10/14/2010 05:34 PM, sunpeng wrote: > We have a table A: > CREATE TABLE A( > uid integer, > groupid integer > ) > Now we use this subsql to get each group's count: > SELECT count(*) as count > FROM A > GROUP BY groupid > ORDER BY groupid > > Then we try to find the group pair with following conditions: > SELECT c.groupid as groupid1,d.groupid as groupid2 > FROM subsql as c, subsql as d > WHERE d.groupid > c.groupid > and d.count > c.count; > > Does that mean subsql will be executed twice? or how to write the > optimized sql? > > What are you trying to discover about groups and their frequency in tablea? Does the numberical value of groupid have any meaning in your system?
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