Thank you Lutz.

>>>Hello all,
>>>
>>>I have a form where two tables will have to be locked. it's a multi-users app.
>>>
>>>I am afraid that if two users get into that form, one could have a lock on table #1 and for whatever reason, the other user could have the lock on the second table.
>>>
>>>How can I make sure that when a given user gets one table locked he will also get the lock on the second table?
>>>
>>>I'm thinking about creating a table where one field would serve to tell me when a locked was made.
>>>
>>>so if field in controlling table tells me that nothing is locked I replace value with .T. so now I know I can lock the second table.
>>>
>>>And other user can't lock until user #1 is finished doing is things.
>>
>>You might want to look into data buffering. Old but extensive article by the late John Koziol at https://www.levelextreme.com/Home/ShowHeader?Activator=23&ID=39374
>>
>>You could also look at VFP transactions if you have to update multiple tables.
>
>But be aware, it hat it own quirks. A write to both tables might fail on one and work on the other. A (not very secure) way is to make sure to always write to both tables, so that the other instance will got a chance to see a change. Usually we write a time stamp on every write. (Optimistic table buffering, row is to automatic for me and pessimistic is just locking). We work on a TS, so the time is synched. Else this might be a problem to consider too. No fail that last 20 odd years, but it's not secure in informatics sense.