>>I want to have a auto-number field in the multi-user environment.
>>I frequently use table buffering in my input forms.
>>How to eliminate duplicate key when inputting ?
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>I do it this way:
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>1. I use INTEGER keys wherever possible.
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>2. I have a table (LASTKEY) with just one record, holding (surprise!) the last used key number.
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>3. I wrote a function (GETNEXTKEY) which opens LASTKEY EXCLUSIVEly, increments the last key number, and returns that value. (Don't forget to close the table, or you will cause quite a deadlock!)
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>4. I specify GETNEXTKEY() as the default value for all key fields.
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>Note: it's OK to share the same LASTKEY for all tables, since with INTEGER fields you have more than 2 billion possible key values, and that allows me not to worry about unused key values either. (If the user starts to insert a new record but cancels it, a key value will go unused. So what?)

There is an example in the TASTRADE application (which was in vfp3, but I haven't seen vfp6 yet). You'll see a table named "keys" and a stored procedure named "newid". This example uses separate records for the keys to separate tables.