Re: Next Number
In article <25dnghINN7b0@emory.mathcs.emory.edu> cheryl@rrad05.army.mil ("cheryl@redriverad-emh1.army.mil") writes:
>When I create a table for use in a database, I tried to have
>a unique numeric key to that table.
>
>for instance:
...
>$ select nxt_nbr into $nxtn
>from next_n where nxt_desc = "nsn_table";
...>/* with nxtn being the next sequential number */
>$ insert into nsn values
>($nxtn, $stock, $mfg, $quantity, ...other fields)>
>then whatever you select the nxt_nbr into
>nxtn=nxtn+1 (whatever the syntax in your version, isql,4gl, esql-c)
>or
>$ update next_n set nxt_nbr to nxt_nbr + 1 where nxt_desc = "nsn_table";
The problem with this is how do you handle multiple entries at the same time?
Let's say USER A and USER B trys to add a record at the same time and the select
return the same count of nxtn to both; or, USER A press <A>dd and takes a break
before pressing the <Esc> key, and meanwhile USER B comes along and <A>dds a
record.
Why not just make the number a serial, in which case the number would be
assigned at the moment the USER presses the <Esc> key. It was also guarantee
each number would be unique.
Bob
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