Check the MySQL error log file (winuser.err) in the MySQL Data directory. Chances are the MySQL user you are using to connect to MySQL has read only access to the table you are trying to update. Either that or you are trying to update data in a table join. The error log file should tell you what is wrong.
You can always write the SQL statement you are trying to execute to the Android log and then copy and paste it into a MYSQL Mgr like Sqlyog and run it there. There is a free community edition for SqlYog that is quite good.
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