sql="select a from b where c=d";
if(cond<1)
sql+=" and e=f";
else if(cond==1)
sql+=" and g=h";
else
sql+=" and i=j";
改为一句SQL
------解决方案--------------------------------------------------------
如果cond是字段可以这样
select a from b where c=d and ((cond<1 and e=f) or (cond=1 and g=h) or(cond>1 and i=j))