JSP为什么只能循环出数据库里的第一条数据
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为什么做循环的时候，只能循环出数据库里的第一条数据，而不能全部循环出来呢。
[解决办法]
Select * from article where pid=" + id;
查出来的值有多少呢
[解决办法]
<%!private void tree(List<Article> articles, Connection conn, int id, int grade) {
String sql = "Select * from article where pid=" + id;
Statement stmt = DB.creatStmt(conn);
ResultSet rs = DB.executeQuery(stmt, sql);
try {
while (rs.next()) {
Article a = new Article();
a.setId(rs.getInt("id"));
a.setPid(rs.getInt("pid"));
a.setRootId(rs.getInt("rootid"));
a.setTitle(rs.getString("title"));
a.setLeaf(rs.getInt("isLeaf") == 0 ? true : false);
a.setPdate(rs.getTimestamp("pdate"));
a.setGrade(grade);
articles.add(a);
System.out.println("-------------" + articles.size() ) ;
if (!a.isLeaf()) {
tree(articles, conn, a.getId(), grade + 1);
}
}
} catch (SQLException e) {
e.printStackTrace();
}
}%>
[解决办法]
- Java code
while (rs.next()) { Article a = new Article();//这里当你循环遍历的时候 你每次都创建新的实体、、、、改成循环外声明
[解决办法]
放在外面没有用。。你检查一下。。List里。。是否ADD进去了。。
[解决办法]
哪有这样的，这不越改越错[解决办法]
那个试试把参数List<Article> articles
在tree方法里重新定义成 articles = new ArrayList<Article>
行不行？
[解决办法]
你可以试试在sql那里打印下你组合起来的sql看看都查询了那些 我怀疑是
if (!a.isLeaf()) {
tree(articles, conn, a.getId(), grade + 1);
}
地方有问题
[解决办法]
首先看你pid为0的数据有几条
其次你pid为0的数据的isLeaf属性是不是false
在次判断你的pid为0的数据时不是有子记录
然后循环判断
你pid的为0的数据就以1条，而他的isLeaf属性又为true，或者就没有子记录，查询出来的当然是1条。
你自己可以这么样一步一步的看结果是什么，会走那条分支走，然后有没有数据添加进来，就知道你为啥是这个结果了啊