Question

i don’t even know if calling it serialized column is right, but i’m going to explain myself, for example, i have a table for users, i want to store the users phone numbers(cellphone, home, office, etc), so, i was thinkin’ to make a column for each number type, but at the same time came to my head an idea, what if i save a json string in a single column, so, i will never have a column that probably will never be used and i can turn that string into a php array when reading the data from database, but i would like to hear the goods and bads of this practice, maybe it is just a bad idea, but first i want to know what other people have to say about

thanks

Answer 1

Short Answer, Multiple columns.

Long Answer:

For the love of all that is holy in the world please do not store mutiple data sets in a single text column

I am assuming you will have a table that will either be

+------------------------------+      +----------------------+
| User |  cell | office | home |  OR  | User | JSON String   |
+------------------------------+      +----------------------+

First I will say both these solutions are not the best solution but if you were to pick the from the two the first is best. There are a couple reasons mainly though the ability to modify and query specifically is really important. Think about the algrothim to modify the second option.

SELECT `JSON` FROM `table` WHERE `User` = ?

Then you have to do a search and replace in either your server side or client side language

Finally you have to reinsert the JSON string

This solution totals 2 queries and a search and replace algorithm. No Good!

Now think about the first solution.

SELECT * FROM `table` WHERE `User` = ?

Then you can do a simple JSON encode to send it down

To modify you only need one Query.

UPDATE `table` SET `cell` = ? WHERE `User` = ?

to update more than one its again a simple single query 

UPDATE `table` SET `cell` = ?, `home` = ? WHERE `User` = ?

This is clearly better but it is not best

There is a third solution Say you want a user to be able to insert an infinite number of phone numbers.

Lets use a relation table for that so now you have two tables.

              +-------------------------------------+
+---------+   |      Phone                          | 
| Users   |   +-------------------------------------+ 
+---------+   | user_name| phone_number | type      |
| U_name  |   +-------------------------------------+
+---------+

Now you can query all the phone numbers of a user with something like this

Now you can query the table via a join

SELECT Users., phone. FROM Phone, Users WHERE phone.user_name = ? AND Users.U_name = ?

Inserts are just as easy and type checking is easy too.

Remember this is a simple example but SQL really provides a ton of power to your data-structure you should use it rather than avoiding it