>>>The bug appears is that vfp sql optimizer takes eof() function as constant
>>>expression and thus refuces to run UPDATE command.
>>
>>>If EOF() is initially .T., update command runs and updates correct records.
>>
>>I don't think this is a bug. A WHERE clause creates a filter condition (which is like a constant expression) that will become a yardstick that will be used to determine what records should be included in the result set or acted upon. In this case RCursor was at EOF, and seeing that VFP didn't have to go any further to determine that 0 records would meet the filter condition.
>
>In this case please explain while following SQL UPDATE updates one record under the same conditions.

 UPDATE Cursor1 ;
>    SET Field1=Field1 ;
>    WHERE !EOF('RCursor')
>

if there is no optimizable parts in WHERE clause,
vfp scans all records and evaluates WHERE condition for each clause.

If there is optimizable construction in WHERE clause, VFP SQL optimizer starts working. There seems to be bug in a SQL optimizer.
It thinks that EOF() function is constant and evaluates it using only the CURRENT updatable record.

If it is initially .F., VFP finds that there is no reacon to scan any record.
If it is initially .T. , VFP scans records and evaluates EOF() again for each record.

For example, if you simply change the order of the two insert statements in my sample program, correct result is returned.