Hi Winfried,
Tables should never be overwritten unless you close one or open another table in the same workarea. However if you have two related tables you might break the relationship between them if you change the index order on the child table. If this isn't causing your strange behavior, then please post more information.

If your form changes to private datasession then you will need to re-set most of the "SET" properties like "SET CENTURY", "SET DELETED" etc. There is a list of the properties that are scoped to the active datasession in Help (SET DATASESSION).

HTH
Barbara

>Hallo,
>have a strange behavior in a form where I use in the Dataenvironment
>two Tables that are in releationship together. Do some Querys with it.
>Questen when will the dataenvironment be overwritten. What dependencys
>are it I set the datasession to Private. It's an single User Application
>Thanks for help
>Winfried