Store Multiple Variables in one Field

D_tunisia

Can anyone advise me on how I can store multiple variables in one field of a table and make them usable?

For example, if the input from a form is:

Varible 1 = 1
Varible 2 = 9
Varible 3 = 3

Then the data should be stored in a single field as 1,9,3.

Thanks in advance.

D_tunisia

Actually, I think I can use the explode() function.

Houdini

Are you sure it might not instead be implode ?

n_wattam

easy one this, by using both functions

on your form use the varible like this,

varible[0] , varible[1] , varible[2] and so on

this will use a single varible and store them as an array

then

$newlist = implode(",",$varible);

use explode if you wish to seperate the single string into an array.

laserlight

Why do you want to store multiple values in a single field in the first place?

n_wattam

laserlight wrote:
Why do you want to store multiple values in a single field in the first place?

why not, i find it very usefull my self at times, eg if you have several multi choice box's in a form and want to keep them together and track of them.

$multichoice1, $multichoice2, $multichoice3 etc then hold the choices selected in each var.

laserlight

why not, i find it very usefull my self at times, eg if you have several multi choice box's in a form and want to keep them together and track of them.

Because it is poor practice in view of database normalisation.

n_wattam

have to disagree on that. does not always work that way. EG.

I was designing a login system the other month, and it has several moduals within the script, i want each modual to have an access right level, as appose to working on group levels.

if i was to have say 30 modules within the script, where i can then assign a user which access he/she can use to what module, creating a table with 30 fields is a bit naff, and impractical.

where as instead i will just store the access right for each they can use in one varible.

Sometimes, personal preference has a part to play, and following the rules doesnt mean its always the right or better way.

n_wattam

so long as you dont go over board and do it left right and centre, maybe.

BETTER EXAMPLE: However something like a multichoice exam, i would say NO!

20 questions with 5 multi choice answers, thats 20x5 fields and 1 table, or 20 tables with 5 fields.

As appose to 1 Table 20 fields, with a string in each fields that contains a verible 5 bits in size, with a 0 or 1.

laserlight

have to disagree on that. does not always work that way.

Indeed, that's what I asked why did the OP want to store multiple values in a single field. It could well have been ignorance rather than sound judgement in making a tradeoff.

I was designing a login system the other month, and it has several moduals within the script, i want each modual to have an access right level, as appose to working on group levels.

if i was to have say 30 modules within the script, where i can then assign a user which access he/she can use to what module, creating a table with 30 fields is a bit naff, and impractical.

A design with 30 fields would be wrong, since then to add a new module you have to modify the table schema.

n_wattam

laserlight wrote:
Indeed, that's what I asked why did the OP want to store multiple values in a single field. It could well have been ignorance rather than sound judgement in making a tradeoff.

Fair Point

laserlight wrote:
A design with 30 fields would be wrong, since then to add a new module you have to modify the table schema.

yup totaly... which was one of the questions i had to face, as the script i was doing was to be open to new modules, where as the mothod i gave, is very flexible, and no order is needed either. 😃

laserlight

20 questions with 5 multi choice answers, thats 20x5 fields and 1 table, or 20 tables with 5 fields.

The problem is that you arent looking at the entities properly.

Offhand, for an MCQ quiz where each question only has one correct answer, the database schema could be something like:

Table: questions
question_id
correct_answer_id
question_text

Table: answers
answer_id
question_id
answer_text

You can have as many questions as needed, and each question can even differ on number of possible answers.

n_wattam

My example was based on a test which does have multipul answers, which do exist (DSA Theory Test). But using that idea or principle to give an example on where or why you would store multipul verables within one.

but to say

Because it is poor practice in view of database normalisation.

as a general comment, its untrue as we have both shown above. 😃

laserlight

My example was based on a test which does have multipul answers, which do exist (DSA Theory Test).

Multiple correct answers?

Then the schema could be changed to:

Table: questions
question_id
question_text

Table: answers
answer_id
question_id
correct_flag
answer_text

But using that idea or principle to give an example on where or why you would store multipul verables within one.

There is no need to store multiple values in a single field, in this case. The database schemas I have presented are more flexible, and allow you to query the database directly, instead of having to parse some string of values yourself.

I'm fairly certain that with more information I can redesign your login system database schema to one that doesnt have to store multiple values in a single field.

as a general comment, its untrue as we have both shown above.

It is true. The only thing is that there are exceptions (though I think there's a group that argues that there are no valid exceptions to the rule, but I personally think that's too extreme).