select * from tmptable order by Tall,age这样是先按Tall从小到大排,同样的Tall再按age从小到大排
如果记录数很多的话,如何快速查找每个相同Tall的年纪的最大值和最小值及同以身高的记录个数?我用如下方法,有没有更好的办法?更改表结构也可以. mQuery.exec("select distinct Tall from tmptable");while(mQuery.next()) { mQuery1.exec("select age from tmptable order by age"); mQuery1.first(); minage=mQuery1.value(0).toInt(); mQuery1.last(); maxage=mQuery1.value(0).toInt(); count=mQuery.size(); }对于每一个元素,
mQuery.exec("select distinct Tall from tmptable");while(mQuery.next())
{
mQuery1.exec("select age from tmptable order by age");
mQuery1.first();
minage=mQuery1.value(0).toInt();
mQuery1.last();
maxage=mQuery1.value(0).toInt();
count=mQuery.size();
}对于每一个元素,