Application of PHP array_diff

Definition and usage:

array_diff() function returns the difference array of two arrays. This array contains all keys that are in the array being compared, but are not in any of the other argument arrays.

In the returned array, the key names remain unchanged.

Syntax

array_diff(<em>array1</em>,<em>array2</em>,<em>array3</em>...);

Parameters	Description
array1	Required. The first array to compare with other arrays.
array2	Required. The array to compare to the first array.
array3	Optional. Other arrays to compare with the first array

Tips and Notes

Tips: One or any number of arrays can be compared to the first array.

Return value

Return value:	Returns the difference array that includes all the differences in the compared array (array1) but not in any other parameter array (array2 or array3 etc.).
PHP version:	4.0.1+

Description:

It says this on the Internet, but when I usually use it, I only know that it is relatively poor, and I don’t think much about it. , but recently I have a problem with label processing in my project. I have used this. I have never used it in this way before. I will record it here. If this happens again in the future, I can also apply it.

My business requirements: Each Customers can have single or multiple tags, and the tag storage needs to be stored as a single or multiple records, so adding is very simple, just add one, or add multiple records in batches, but modification is different, that is Mainly the latest ones. In layman's terms, if the old tags do not contain new tags, then we have to add new tags and delete the old tags. But there are other situations: If some of the old tags contain new tags. One or more, then the problem is, when we go out and the old tag does not contain the new tag, add the new tag that does not exist in the old tag. I am probably a little confused, let me explain with an example:

Example:

Old tag: [A, B, C ]                                                                                                                                                                                                                                                                                                  ​Add, delete A and B in the old tags

Like the above situation, the first time I thought was to delete all the old tags and then add new ones, that would be fine, but if I think about it carefully, delete Ah, what is the concept? I know that we are very cautious about deleting data in the data table. Besides, in the project, each user may have several tags. If there are many, do we still need to delete them? ? Also, when we delete table data, we will find that the size of the data file has not been reduced. This is because fragments are left in the data file after the deletion operation. So this method is not advisable!

Then maybe I will think of traversing them and comparing them, adding or deleting without comparison, I found This is particularly troublesome. Both data must be traversed and the data must be compared one by one. Less data is okay, but too much data is not good!

So this time we thought of a way, which is to use the PHP function array -diff()

For example:

1: array_diff (old, new) => [A, B] => Delete (modify status to: disabled state) 2: array_diff (new, old) => [D,E] => Add

Does the above solve the problem? It not only deals with the old ones, but also adds the new ones. Isn’t it good...

The above has introduced the application of PHP array_diff, including aspects of it. I hope it will be helpful to friends who are interested in PHP tutorials.