php - 如何显示类别及其子类别

Question

我有这样的 table

cat:
----
cat_id    name
---------------
1        cat-1
2        cat-2 


sub-cat:
--------

id    cat_id    name
-------------------------
1       1       sub-cat-1
2       1       sub-cat-2
3       2       sub-cat-3
4       2       sub-cat-4

我需要像使用 PHP 一样的输出

cat-1
 sub-cat-1
 sub-cat-2
cat-2
 sub-cat-3
 sub-cat-4

我的查询是

SELECT * FROM `cat` 
        JOIN `sub-cat`  ON cat.cat_id = sub-cat.cat_id

Answer 1

你可以使用这个代码

$sql = mysqli_query("SELECT * FROM `cat` ");
while($row = mysqli_fetch_array($sql))
{
   echo "cat ".$row['name'];
   $sql1 = mysqli_query("SELECT * FROM `sub-cat` where id = ".$row['cat_id']);
   while($row1 = mysqli_fetch_array($sql1))
   {
        echo "sub-cat ".$row1['name'];
   }
}