ORA-01668
        standby database requires DROP option for offline of data file
        
        
        Cause
        Attempting to take a datafile offline in a standby database without specifying the DROP option. Files that are offline in a standby database are not recovered, and are likely to be unusable if the standby is activated. Note that specifying DROP does not prevent bringing the file online later.
        Action
        Specify the DROP option or leave the file online.
        
     
    
    
        ORA-01668
        standby database requires DROP option for offline of data file
        
        
        Cause
        Attempting to take a datafile offline in a standby database without specifying the DROP option. Files that are offline in a standby database are not recovered, and are likely to be unusable if the standby is activated. Note that specifying DROP does not prevent bringing the file online later.
        Action
        Specify the DROP option or leave the file online.
        
     
    
    
        ORA-01668
        standby database requires DROP option for offline of data file
        
        
        Cause
        Attempting to take a datafile offline in a standby database without specifying the DROP option. Files that are offline in a standby database are not recovered, and are likely to be unusable if the standby is activated. Note that specifying DROP does not prevent bringing the file online later.
        Action
        Specify the DROP option or leave the file online.