How render a Tree in html + php(codeIgniter)

问题

I have an adjacency model list and this is the query:

SELECT t1.FIO AS lev1, t2.FIO AS lev2, t3.FIO AS lev3, t4.FIO AS lev4, t5.FIO AS lev5, t6.FIO AS lev6, t7.FIO AS lev7, t8.FIO AS lev8, t9.FIO AS lev9, t10.FIO AS lev10, t11.FIO AS lev11, t12.FIO AS lev12, t13.FIO AS lev13, t14.FIO AS lev14, t15.FIO AS lev15, t16.FIO AS lev16, t17.FIO AS lev17, t18.FIO AS lev18, t19.FIO AS lev19, t20.FIO AS lev20, t21.FIO AS lev21, t22.FIO AS lev22, t23.FIO AS lev23, t24.FIO AS lev24 FROM users AS t1 LEFT JOIN users AS t2 ON t2.parent_id = t1.id LEFT JOIN users AS t3 ON t3.parent_id = t2.id LEFT JOIN users AS t4 ON t4.parent_id = t3.id LEFT JOIN users AS t5 ON t5.parent_id = t4.id LEFT JOIN users AS t6 ON t6.parent_id = t5.id LEFT JOIN users AS t7 ON t7.parent_id = t6.id LEFT JOIN users AS t8 ON t8.parent_id = t7.id LEFT JOIN users AS t9 ON t9.parent_id = t8.id LEFT JOIN users AS t10 ON t10.parent_id = t9.id LEFT JOIN users AS t11 ON t11.parent_id = t10.id LEFT JOIN users AS t12 ON t12.parent_id = t11.id LEFT JOIN users AS t13 ON t13.parent_id = t12.id LEFT JOIN users AS t14 ON t14.parent_id = t13.id LEFT JOIN users AS t15 ON t15.parent_id = t14.id LEFT JOIN users AS t16 ON t16.parent_id = t15.id LEFT JOIN users AS t17 ON t17.parent_id = t16.id LEFT JOIN users AS t18 ON t18.parent_id = t17.id LEFT JOIN users AS t19 ON t19.parent_id = t18.id LEFT JOIN users AS t20 ON t20.parent_id = t19.id LEFT JOIN users AS t21 ON t21.parent_id = t20.id LEFT JOIN users AS t22 ON t22.parent_id = t21.id LEFT JOIN users AS t23 ON t23.parent_id = t22.id LEFT JOIN users AS t24 ON t24.parent_id = t23.id LEFT JOIN users AS t25 ON t25.parent_id = t24.id WHERE t1.id = 16

this is a query to make 24 levels of depth using the adjacency model list

and after that i make this:

<? for($i = 0; $i < $query->num_rows(); $i++): ?>
<? $row = $query->row($i); ?>
    <? for($n = 1; $n < 25; $n++): ?>
    <? $lev = "lev$n"; ?>
    <?= $row->$lev; ?>
    <? endfor; ?>
<? endfor; ?>

it render just the fields of every row, and i really don't know hot make it hieararchical, i am using codeigniter, what is better to use here rows or objects??

i need to make something like this:

root_parent {
   parent_1 {
      child_1.name
      child_2.name
      child_3.name
   }

   parent_2 {
      child_1.name
      child_2.name
      child_3.name
   }

   parent_3 {
      child_1.name
      child_2.name
      child_3.name
   }
}

without repeatings is that possible?

回答1:

Seems a bit complicated and inflexible what you're doing here Gilles. Would it not be better to create your database table with each row having its own category_id and a parent_id? ie give the top level parents a parent_id of 0 and the children take the parent_id of their parent's category_id. This would give you unlimited depth and will be easier to code when you're rendering the tree. For example:

SQL for your first level of hierarchy -

SELECT * FROM (your_table) WHERE parent_id=0

SQL for your second level of hierarcy -

SELECT * FROM (your_table) WHERE parent_id=(category_id of first level)

SQL for your third level of hierarcy -

SELECT * FROM (your_table) WHERE parent_id=(category_id of second level)

and so on...

来源：https://stackoverflow.com/questions/11385250/how-render-a-tree-in-html-phpcodeigniter

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