How to use a unique number as a primary key instead of a composite key

[chathura86]

hi

i have a database structure where every table has composite primary key

it is like this
for all the tables primary key is like a number (an auto increment) and the pc_id

eg.

Table Author
AutherId, pc_id, .............. other columns
1 100 .......................................
2 100 .......................................
1 110 .......................................

Table Book
BookId, pc_id, AutherId, AuthorPcId, ............... other columns
1 100 1 100 ............................
2 110 1 100 ............................

is was thinking like making a unique id (manually) and using that as the primary key, but the key is like 32 digit number, is there any drawbacks using
such a big int as the primary key
or is there any other workaround for this issue

Regards

[Atli]

Why would you want to use such a big number?

If you want to use a 32 digit number, you would need to store it as a string. No integer type can hold so many digits. That is of course a performance hit, versus simple integer PKs, and it would also take much more space.

[chathura86]

@Atli
ok in that case what is the best method to build a unique id (pc_id is a 6digit number) so i want the AutherId generated in a way that the combination will be uniqe, i was planing to use PHP uniqid() converted a int and append the pc_id

what other ways are possible to make this unique id

regards