sql error: select id,classid,ttid,onclick,plnum,totaldown,newspath,filename,userid,username,firsttitle,isgood,ispic,istop,isqf,ismember,isurl,truetime,lastdotime,havehtml,groupid,userfen,titlefont,titleurl,stb,fstb,restb,keyboard,title,ftitle,daan,newstime,titlepic,smalltext,diggtop from ***_ecms_news order by rand() limit 10
(x y)(x²-xy y²)
=x(x²-xy y²) y(x²-xy y²)
分配律=x3-x2y xy2 x2y-xy2 y3
再次分配律=x³ y³
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