Allow Special Characters Like & in Oracle

In SQL*Plus and SQL Developer the & character starts a substitution variable, so a statement containing it (such as 'AT&T') stops and asks for a value. Turn the DEFINE setting off to treat & as ordinary text.

-- & is the default DEFINE character; switching DEFINE off lets you use it in text
SET DEFINE OFF;

-- now this runs without prompting for a value for T
INSERT INTO companies (name) VALUES ('AT&T');