? 代表的是参数,ql执行时的语句就是select object(o) as o from entitybean where o.name like‘%ejb%' 比如我传来的参数是 ejb ,则要查询的是所有包含ejb的字符串,比如 studyejb ,ejbstudy,studyejbstudy 。在sql语言里很好实现的,但我现在要用ejb。
并且like‘%ejb% 也可以查询null的字符串,如果没有这个,?不知各位是怎么解决的呢?
String sel="select * from leechdom where spec like ?"; PreparedStatement stmt=con.prepareStatement(sel); stmt.setString (1,new String(“%土%”.getBytes(),"iso-8859-1")); ResultSet rs=stmt.executeQuery()
String sel="select * from leechdom where spec like ?"; PreparedStatement pstmt=con.prepareStatement(sel); pstmt.setString (1,new String(“%土%”.getBytes(),"iso-8859-1")); ResultSet rs=stmt.executeQuery()
like‘?%’,逻辑上有什么不同吗?逻辑上都是把任何不为空的字符串都elect 进来。
PreparedStatement stmt=con.prepareStatement(sel);
stmt.setString (1,new String(“%土%”.getBytes(),"iso-8859-1"));
ResultSet rs=stmt.executeQuery()
PreparedStatement pstmt=con.prepareStatement(sel);
pstmt.setString (1,new String(“%土%”.getBytes(),"iso-8859-1"));
ResultSet rs=stmt.executeQuery()