Question

For each ad, I allow users to choose up to 5 tags. Right now, in my database, I have it like…

Posting_id     TagID
    5            1
    5            2 
    5            3
    6            5
    6            1

But i was thinking if I should make it like…

    Posting_id     TagID
    5              1 2 3 
    6              5 1

Then first option is much easier to insert and retrieve data. But if I have 100 posts with 3 tags each, that’s 300 rows…so ALOT more rows

The second option requires using explode() impode(), etc but it is much cleaner.

Which option should I do and why? thanks!

EDIT: The first way is better!

Answer 1

Use the first option because the second option makes it difficult to index the TagID column effectively. If you ever want to query your data on for a specific numeric value stored in the TagID column (and I’m betting you will), you’ll get poor performance out of the second option.