计算每个关键字在多少行中出现的最有效方法是什么。例如给定以下列表:cat,dog,basement,parrot,whale,dolphins并给定以下简单数据库:IDTEXTDATA1Thecatisinthebasement,thecatisnotontheroof.2Thedogisgoinghome.3Thebirdsareflyinginthesky.4Thedolphinsareswimmingintheocean,ireallylikedolphins.5Themouseliveinthebasement.结果应该是:cat=1(twooccurrencesinonero