PHP implementation Query Multilevel classification of program code

The database structure design of the algorithm is the simplest. Category A field ID in the table, a field FID (parent ID). This allows you to determine the level of content based on where id = FID, using recursion to the top

Let's find the array first.

The code is as follows

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<?php $a = Array ( ' Aaaaaa ' => Array ( ' Aaaaaa ' => Array ( ' 111111 ', ' 222222 ', ' 333333 ' ), ' BBBBBB ' => Array ( ' 111111 ', ' 222222 ', ' 333333 ' ), ' CCCCCC ' => Array ( ' 111111 ', ' 222222 ', ' 333333 ' ), ), ' BBBBBB ' => Array ( ' Aaaaaa ' => Array ( ' 111111 ', ' 222222 ', ' 333333 ' ), ' BBBBBB ' => Array ( ' 111111 ', ' 222222 ', ' 333333 ' ), ' CCCCCC ' => Array ( ' 111111 ', ' 222222 ', ' 333333 ' ), ), ' CCCCCC ' => Array ( ' Aaaaaa ' => Array ( ' 111111 ', ' 222222 ', ' 333333 ' ), ' BBBBBB ' => Array ( ' 111111 ', ' 222222 ', ' 333333 ' ), ' CCCCCC ' => Array ( ' 111111 ', ' 222222 ', ' 333333 ' ), ), ); foreach ($a as $k => $v) { echo $k. " <br> "; if (Is_array ($v)) { foreach ($v as $key => $val) { echo "". $key. " <br> "; //     } if (Is_array ($val)) { foreach ($val as $kkk => $vall) { echo "". $vall. " <br> "; } } } echo "<br>"; } Code ******/for/*******mysql query infinite level classification /*** $sql = "Select A.title as Big, b.title as small From Largetitle as a left JOIN Smalltitle as B on A.id=b.largeid "; $a = array (); $r = mysql_query ($sql); while ($arr = Mysql_fetch_array ($r)) { $a [$arr [' big ']] = $arr [' small ']; } ***/ ?>

All right, let's read the database and then read it recursively.

Categories, such as category, fields have Id,parentid,title

The code is as follows

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Inquire $dsql->setquery ("SELECT * from category ORDER by SortOrder ASC"); $dsql->execute (' parentlist '); $array = Array (); $parentlist = Array (); while ($rs = $dsql->getobject (' parentlist ')) { if ($rs->parentid = = 0) { $parentlist [$rs->id] = (array) $rs; } Else { $array [$rs->id] = (array) $rs; } } $parentlist = Cat_options ($parentlist, $array); We're asking for an array of results An array of $list parent categories $array is an array of all categories except the parent category Function cat_options (& $list,& $array) { foreach ($list as $key => $arr) { foreach ($array as $k => $value) { if ($value [' parentid '] = = $arr [' id ']) { $list [$key] [' children '] = $value; Unset ($array [$k]); } } } foreach ($list as $key => $arr) { if (Is_array ($arr [' Children ']) && count ($arr [' Children ']) > 0) { $list [$key] [' children '] = cat_options ($list [$key] [' Children '], $array); } } return $list; }

Other methods, set the FID field type to varchar, the parent class ID is concentrated in this field, separated by symbols, such as: 1,3,6
This makes it easier to get the IDs of the superior categories, and when querying the information under the classification,
You can use: SELECT * from category WHERE pid like "1,3%".

code is as follows

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-- --table's structure ' category ' -- CREATE table IF not EXISTS ' category ' ( ' id ' int (one) not NULL Auto_increme NT, ' type ' int (one) not null COMMENT ' 1 for Article Type 2 for product Type 3 for download type ', ' title ' varchar NOT NULL, ' lft ' int (one) not N ull, ' RGT ' int (one) not null, ' lorder ' int (one) not null COMMENT ' sort ', ' create_time ' int (one) not NULL, P Rimary KEY (' id ') ) Engine=innodb DEFAULT Charset=utf8 auto_increment=10; -- --Export the data in the table ' category ' -- INSERT into ' category ' (' id ', ' type ', ' title ', ' LfT ', ' rgt ', ' lorder ', ' CR Eate_time ') VALUES (1, 1, ' Top columns ', 1, 1, 1261964806), (2, 1, ' Company Profile ', X, M, 1264586212), (3, 1, ' News ', A, 1264586226, (4, 2, ' company Products ', ten, One, 1264586249), (5, 1, ' Honors ', 8, 9, M, 1264586270), ( 6, 3, ' data downloads ', 6, 7, 1264586295, (7, 1, ' recruitment ', 4, 5, 1264586314), (8, 1, ' Message board ', 2, 3, 50, 1264586884), (9, 1, ' president ', 1267771951, n); The /** * Displays the tree, displaying all nodes. * 1, get the left and right values of the root node first (the default root is the title of the "top-level directory"). * 2, query the left and right values in the root node of the value range of records, and sorted by the left value. * 3, if the right value of this record is greater than the previous record of the right value is a subcategory, the output time with spaces. * @return Array **/ function Display_tree () { Get the value to the left and right of root $arr _LR = $this->category->where ("title = ' top Column '")->find (); Print_r ($arr _LR); if ($arr _lr) { $right = Array (); $arr _tree = $this->category->query ("Select ID, type, title, RGT from category WHERE LfT >=". $arr _lr[' LfT ']. " and LfT <= ". $arr _lr[' RGT ']." ORDER by LfT "); foreach ($arr _tree as $v) { if (count ($right)) { while ($right [count ($right)-1] < $v [' RGT ']) { Array_pop ($right); } } $title = $v [' title ']; if (count ($right)) { $title = ' | | '. $title; } $arr _list[] = array (' ID ' => $v [' id '], ' type ' => $type, ' title ' => str_repeat (', Count ($right)). $title, ' name ' = > $v [' title ']]; $right [] = $v [' RGT ']; } return $arr _list; } }

All right, so long as this all sorts of categories can be queried at once, instead of recursion.