java - 结果集中没有数据

Question

我有以下代码:

string query = select COUNT(*) from  TRACKER where TYPE = ? and LAST_MODIFIED_TIME > LAST_RETREIVED_TIME;
prepStmt = connection.prepareStatement(query);
            prepStmt.setString(1, "xml");

            resultset = prepStmt.executeQuery();

            resultset.next();   
            int rowcount = resultset.getInt("COUNT(*)"); 

在数据库中，我有 1 行用于上述查询，但在代码中，我得到 rowcount= 0。有什么帮助吗？

Answer 1

尝试为 count(*) 指定一个别名:

String query = "select COUNT(*) as count from  TRACKER where TYPE = ?"+
               " and LAST_MODIFIED_TIME > LAST_RETREIVED_TIME";
prepStmt = connection.prepareStatement(query);
prepStmt.setString(1, "xml");
resultset = prepStmt.executeQuery();
resultset.next();   
int rowcount = resultset.getInt("count");