Unknown table 'book' in field list
sqlStr="select book.id,book.bookname,book.bookclass,bookclass.classname,"+
"book.author,book.publish,book.bookno,book.content,book.prince,book.amount,"+
"book.Leav_number,book.regtime,book.picturefrombook,bookclass"+
"wherebook.Bookclass=bookclass.Id";
------解决方案--------------------------------------------------------
sqlStr="select book.id,book.bookname,book.bookclass,bookclass.classname,"+
"book.author,book.publish,book.bookno,book.content,book.prince,book.amount,"+
"book.Leav_number,book.regtime,book.picture from book,bookclass"+
"where book.Bookclass=bookclass.Id";
丢失空格