在单个SQL行中存储多个值

Question

I'm trying to modelize a configuration table for my application, and I'd like to have your opinion on how to store multiple values for a configuration value.

For example, how to store the available languages? How to store the allowed files extensions, etc.?

I'd like to have a field key and a field value in my table configuration , but I have multiple ways of storing the value:

• Serializing a PHP array and storing this in one row,
• Storing all values separated by a comma, like this 1,4,9,42
• Having multiple rows with the same key but different values . I don't see how I could get this working, it would be very unusable...

Thanks for your help :)

Answer 1

Leaving aside any discussion of whether or not this is a good idea, many people do this. A very common approach is to have a 'blob' field on a 'configuration' table and store your data in JSON format. You'll serialize and deserialize yourself but that's no big deal.

Answer 2

If you want to store your configuration in database (it's not recommended , but it makes sense if you have many instances of your application) - let's analyze it:

1. Approach with storing multiple rows with same key - let's forget about it ;)

2. Storing many values separated by , - that one would make some problems if you'll need to store value with coma (for example: 10,000 as ten thousand). Then you'll need to modify it to store values like in CSV file encapsulated with " .

3. Best idea - storing serialized PHP values . As your app is written in PHP that would be the best native method. Using this approach would be as easy as:

   $configValue=unserialize(getMyValueFromDb("myKey")); //or saving it after change $configValue="new value"; saveMyValueToDb(serialize($configValue));

Also - PHP serialize and unserialize take care about escaping values and convert it properly so you don't need to worry about some coma-separated-string wrongly split with explode .