我有张贴表
+----+-------+--------------+
| Id | Name | Message |
+====+=======+==============+
| 1 | John | John's msg |
| 2 | Marco | Marco's msg |
| 3 | Ivan | Ivan's msg |
+----+-------+--------------+
评论表，PostId 为外键
+----+-------+--------------+--------+
| Id | Name | Comment | PostId |
+====+=======+==============+========+
| 1 | John | John's msg | 2 |
| 2 |Joseph |Joseph's msg | 2 |
| 3 | Ivan | Ivan's msg | 2 |
| 4 |Natalie|Natalie's msg | 1 |
+----+-------+--------------+--------+
创建闭包表以保持评论层次结构，如下所述：http: //karwin.blogspot.ba/2010/03/rendering-trees-with-closure-tables.html
封闭表
+----------+-------------+
| ancestor | descendant |
+==========+=============+
| 1 | 1 |
| 1 | 2 |
| 1 | 3 |
| 4 | 4 |
+----------+-------------+
为了在 PHP 中创建祖先>后代关系，我使用了这个查询
`select c.* from comments c join closure t on (c.id = t.descendant ) where c.postid=2`
我从评论表中获得了第 3 条评论的结果。但我想在这样的网页上显示这个：
Post Id=2
Comment id=1
Comment id=2
Comment id=3
我不知道如何告诉 PHP 谁是祖先，谁是后代。这是我最好的尝试：
$sql = "select c.* from comments c join closure t on
(c.id = t.descendant ) where c.postId=2";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
while($row = $result->fetch_assoc()) {
echo "Name: " . $row["name"]."". "Message:" . $row["comment"].";
}
} else {
echo "No comments yet";
}
但它只显示所有评论。需要一种方法来识别评论何时是后代。
while($row = $result->fetch_assoc()) {
if (ascendant){
echo "ascendant comment"
}
else{
echo "tab"."descendant comment"
}
}