正在阅读：Java、XML与数据库编程实践(四)Java、XML与数据库编程实践(四)

 protected boolean alreadyin(String tname,String colname, String value)

    {      

        int result;

        ResultSet rst=null;

        try {

        //执行SQL语句

        String query = "select "+colname+" from "+tname+" where "+colname+"='"+value+"'";

        Statement statement = connformax.createStatement();

        rst = statement.executeQuery( query );

        if(rst.next())

        {

            statement.close();

            rst.close();

            return true;

        }      

     }

     catch ( SQLException sqlex ) {

        sqlex.printStackTrace();

        return false;

     }

     return false;    

    }