Efficiency Question

[Aaron]

I've developed a permissions system as part of a the admin side a website. There are dozens of possible permissions which can be granted to a user, either individually or as part of a group. On any given page load, up to five of these permissions may be checked for. Would it be better to store the permissions in a table with the form:

ID User Permission
1 1 1
1 1 2
1 1 3
1 2 7


or


ID User Permission
1 1 1,2,3
1 2 7
1 3 10,42


And just get the the whole row and search in the permission string for the desired permission number?

Thanks

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[Giraffe]

Assuming it's a on/off permission thing, you'd do better packing them all into an integer, then doing bitmask tests to see which bits were set.

0 = no bits set
1 = first bit set
2 = second bit set
3 = first and second bit set
...
31 = first 5 bits set

etc.

[Edit: I assume that's MySQL? If so... [URL=http://www.mysql.com/documentation/mysql/bychapter/manual_Reference.html#Bit_functions]http://www.mysql.com/documentation/mysql/bychapter/manual_Reference.html#Bit_functions[/ URL] ]
[Edit: To test for the nth bit set, Bitwise OR the number with 2^n (i.e. 1, 2, 4, 8, 32, ... - that's n starting at 0 btw)]

[This message has been edited by Evil_Giraffe (edited October 08, 2003).]

[This message has been edited by Evil_Giraffe (edited October 08, 2003).]

[Dormouse]

Gir beat me to it, listen to him.

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[Aaron]

I like the bitwise operations, that would be much better than either system (in several ways). I'm actually using SQL server, but I may aswell just get the value and let the script handle the operators.

Thanks for the help.

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