Cause
An attempt was made to repeat the drop column option in a single statement.
An attempt was made to repeat the drop column option in a single statement.
Separate drop column options into different statements and resubmit statements.
Try the following links for this error:
http://docs.oracle.com/cd/E16655_01/server.121/e26079/e12700.htm
https://community.oracle.com/message/2413687
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