int型的话应该写成
int k=rs1.getInt(4)+1;
String new1="update card set borrownum="+k+" where cardnum="+cardnum;
或者直接就
String new1 = "update card set borrownum=borrownum+1 where cardnum=" + cardnum;
int k=rs1.getInt(4)+1;
String new1="update card set borrownum="+k+" where cardnum="+cardnum;
或者直接就
String new1 = "update card set borrownum=borrownum+1 where cardnum=" + cardnum;
String new1="update card set borrownum='"+ k +"' where cardnum='"+cardnum+"'";
stmt.executeUpdate(new1);
你上面的做法可以实现这个功能
int k=rs1.getInt(4)+1
String的则:
int k=Integer.parseInt(rs1.getString(4))+1String new1="update card set borrownum='"+k+"' where cardnum='"+cardnum+"'";
stmt.executeUpdate(new1);