Update:
I've followed post
http://forums.mysql.com/read.php?65,10608,231203#msg-231203
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Add a field to table of type datetime default null
Update link in access
write and run update query to populate this field with now()
Then change this field to type timestamp and default value current_timestamp.
Relink in access.
Job done..
The key to this is that the field is populated... for the timestamp to work.
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and it works. But ....
access database has corrupt. So next time I've entered the table I could not see any record (odbc error). What I've done:
1. Create a new empty database
2. Link all the tables
3. Tools/Utility/Administer linked tables (I'm not sure since my access has the menu in spanish)-> select all and update
4. Check the tables
5. Import everyting but tables from the original database
By the moment it's working