ORA-01754: a table may contain only one column of type LONG

admin

ORA-01754: a table may contain only one column of type LONG
Cause: An attempt was made to add a LONG column to a table which already
had a LONG column. Note that even if the LONG column currently in the table
has already been marked unused, another LONG column may not be added until
the unused columns are dropped.
Action: Remove the LONG column currently in the table by using the ALTER
TABLE command.