Error starting at line : 9 File @ /oracle.sqlIn command -alter table RESERVATIONS modify ReservationTime TIME NULLError report -ORA-22858: invalid alteration of datatype22858. 00000 - "invalid alteration of datatype"*Cause: An attempt was made to modify the column type to object, REF, nested table, VARRAY or LOB type.*Action: Create a new column of the desired type and copy the current

The error message you're seeing is due to an attempt to modify the datatype of a column in a way that Oracle doesn't allow. Oracle doesn't permit changing the datatype of a column to an object, REF, nested table, VARRAY, or LOB type using the ALTER TABLE command.

Here's a step-by-step guide on how you can resolve this:

1. Add a new column with the desired datatype: You can do this with the following command:

   ALTER TABLE RESERVATIONS ADD (New_ReservationTime TIME);
   

2. Copy the data from the old column to the new one: You can do this with the following command:

   UPDATE RESERVATIONS SET New_ReservationTime = ReservationTime;
   

3. Verify that the data has been copied correctly.

4. Drop the old column: You can do this with the following command:

   ALTER TABLE RESERVATIONS DROP COLUMN ReservationTime;
   

5. Rename the new column to the old column's name: You can do this with the following command:

   ALTER TABLE RESERVATIONS RENAME COLUMN New_ReservationTime TO ReservationTime;
   

Please note that this process can take a significant amount of time and resources if the table is large, and it will require enough space in your tablespace to hold two copies of the column data temporarily. Also, any indexes, constraints, or triggers on the old column will need to be recreated for the new column.

The error message you're seeing is due to an attempt to modify the datatype of a column in a way that Oracle doesn't allow. Oracle doesn't permit changing the datatype of a column to an object, REF, nested table, VARRAY, or LOB type using the ALTER TABLE command.

Here's a step-by-step guide on how you can resolve this:

1. Add a new column with the desired datatype: You can use the following command to add a new column:

   ALTER TABLE RESERVATIONS ADD (New_ReservationTime TIME);
   

2. Copy the data from the old column to the new one: You can use the following command to copy the data:

   UPDATE RESERVATIONS SET New_ReservationTime = ReservationTime;
   

3. Verify the data in the new column: You can use the following command to verify the data:

   SELECT New_ReservationTime FROM RESERVATIONS;
   

4. Once you've verified the data, you can drop the old column: You can use the following command to drop the old column:

   ALTER TABLE RESERVATIONS DROP COLUMN ReservationTime;
   

5. Finally, you can rename the new column to the old column's name: You can use the following command to rename the column:

   ALTER TABLE RESERVATIONS RENAME COLUMN New_ReservationTime TO ReservationTime;
   

Please replace TIME with the actual datatype you want to use. Oracle doesn't support the TIME datatype. You might want to use DATE or TIMESTAMP instead.