When importing a backup you might have run into the problem that the ampersands (&) or colon () characters are used as bind variables in PL/SQL. This is actually no real problem, as you can simply change the substitution character using the DEFINE setting in SQL*Plus:

SET DEFINE ~

The usual substitution mechanism an ampersands would trigger, is now suppressed.

Other methods:
Define an escape character:

SET ESCAPE '\'
SELECT '\&abc' FROM dual;

Don’t scan for substitution variables:

SET SCAN OFF
SELECT '&ABC' x FROM dual;

Another way to escape the & would be to use concatenation, which would not require any SET commands -

SELECT 'Laurel ' || '&' || ' Hardy' FROM dual;

Use the 10g Quoting mechanism:

Syntax
 q'[QUOTE_CHAR]Text[QUOTE_CHAR]'
 Make sure that the QUOTE_CHAR followed by an ' doesn't exist in the text.
SELECT q'{This is Orafaq's 'quoted' text field}' FROM DUAL;

You can also turn off substitutions by setting define to off:

SET DEFINE OFF

When you need it, just turn it on again:

SET DEFINE ON

Reference:

http://kwatog.com/blog/oracle/enable-disable-bind-variable-in-sqlplus/