PHP Unlimited Classification examples (imitation Taobao product classification)

CREATE TABLE ' type ' ( ' id ' int (one) not NULL auto_increment, ' FID ' int (one) not NULL DEFAULT ' 0 ', ' Name ' varchar (not NULL), PRIMARY KEY (' id ') ) Copy Code Second, add several top-level categories to add INSERT into ' type ' (' id ', ' fid ', ' name ') VALUES (NULL, ' 0 ', ' phone '); INSERT into ' type ' (' id ', ' fid ', ' name ') VALUES (NULL, ' 0 ', ' computer '); INSERT into ' type ' (' id ', ' fid ', ' name ') VALUES (NULL, ' 0 ', ' shoes '); INSERT into ' type ' (' id ', ' fid ', ' name ') VALUES (NULL, ' 0 ', ' clothes '); Copy Code Here Fid=0 is representative of the top category Then add several subcategories for {computer} INSERT into ' type ' (' id ', ' fid ', ' name ') VALUES (null, ' 2 ', ' Desktop '), (null, ' 2 ', ' notebook '); Copy Code Here fid=2,2 this ID is the ID of the category {computer}, if it is a subcategory that adds {shoes} fid=3 the same as {notebook} to add subcategories fid=6 INSERT into ' type ' (' id ', ' fid ', ' name ') VALUES (null, ' 6 ', ' Ausu '), (null, ' 6 ', ' hp '); Copy Code Third, delete if you want to delete the category {notebook}, you can: DELETE from ' type ' WHERE ' ID ' =6 Copy Code {Notebook} sub-classification also remember to do the corresponding processing Function del ($FID) { $sql = "SELECT * from ' type ' WHERE ' fid ' = $fid"; $rs =mysql_query ($sql); for ($i = 0; $i < count ($rs); $i + +) { $sql = "DELETE from ' type ' WHERE ' id ' ={$rs [$i] [' ID ']}"; mysql_query ($sql); Del ($rs [' id ']);//recursion } } Del (6);//Perform operation Copy Code Why is it so troublesome to use recursion instead of deleting it directly DELETE from ' type ' WHERE ' FID ' =6 Copy Code So you can delete {Ausu}, {hp} directly? But suppose {Ausu} has a subcategory {A1},{A1} that also has a subclass {A2}, which cannot be completely deleted without recursion. Third, find 1. Find subcategories for {computer} SELECT * from ' type ' WHERE ' FID ' =2 Copy Code 2. Find all sub-categories for {computer} Function sel ($FID) { $sql = "SELECT * from ' type ' WHERE ' fid ' = $fid"; $rs =mysql_query ($sql); for ($i = 0; $i < count ($rs); $i + +) { echo $rs [$i] [' name ']; SEL ($rs [$i] [' id ']);//recursion } } SEL (2); Copy Code Iv. Practical application Add a field ' tid ' to the data table, and the field value is the ID of the category ' type ' table to which the record belongs. Must be ID cannot be name, because the value of name may change. For example, query for items that belong to the {computer} Category: SELECT * from ' goods ' WHERE ' tid ' =2 Copy Code Let's introduce these and hope to help you.

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