PHP: prevent duplicated tags in Mysql


I have MySql Table For Tags Like This:

| id |   name    |
| 1  |   Linux   |
| 2  |  Windows  |
| 3  |   Unix    |
| 4  |    Dos    |
| 5  |  FreeBSD

In News Page User add New Tags Like This:


Now,Linux Previously added, So I need To addONLY OpenBSD and Test Into Tags Table. My Mean Is: how toINSERT tags if User tags is New?!




  1. Put aUNIQUE constraint on thename column.
  2. UseINSERT IGNORE so that inserting a column wherename already exists simply skips that row. eg:

    INSERT IGNORE INTO tags (name) VALUES ('Linux'), ('OpenBSD'), ('Test');
  3. Because you have different casings in your data [eg:linux vsLinux] you either need to make sure that you are using a case-insensitive coallation in your database likeutf8_latin1_ci [ci stands for case-insensitive] or be sure to usestrtolower() on your data prior to inserting it.



Like Jay suggested, normalise the data, then make the columnUNIQUE, and use something likeINSERT IGNORE INTO yourTags(name) VALUES(?),(?),(?) (and send in the three values as parameters). I'm also assuming that the ID column isAUTO INCREMENT.

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