ALTER TABLE Statement returning an error

[Pablo Grande]

I've checked and double checked the syntax, but it seems the ALTER TABLE statement keeps returning an error.

ALTER TABLE emp_pes605
ADD salary number(6);

Error occured. Recheck your SQL statement

Also, when I try to insert data into the table, it adds two records instead of only one.

Any help would be appreciated.

[Pablo Grande]

I also just tried to update a record. It said the command was executed successfully, but the field is still blank.

[Pablo Grande]

Please disregard. I found another resource for advancing my SQL skills.

[adampv]

Mind sharing what you found?