Oracle/PLSQL: ORA-00911 Error

Error:

Cause:

Action:

1. This error occurs when you try to use a special character in an SQL statement. If a special character other than $, _, and # is used in the name of a column or table, the name must be enclosed in double quotations.
2. This error may occur if you've pasted your SQL into your editor from another program. Sometimes there are non-printable characters that may be present. In this case, you should try retyping your SQL statement and then re-execute it.
3. This error occurs when a special character is used in a WHERE clause and the value is not enclosed in single quotations.

For example, if you had the following SQL statement:

SELECT * FROM suppliers
WHERE supplier_name = ?;

You would receive the following error message:

You could correct this error by enclosing the ? in single quotations as follows:.

SELECT * FROM suppliers
WHERE supplier_name = '?';