Use of & in sql

Question

how can i use the & symbol before the columnname. then asks to user to input the columnname.

Answer 1

It doesn't do or mean anything special in SQL string literal. It is just stands for itself; i.e. the ampersand character. So like '&A%' means a string that starts with '&A'.
Apparently (Joshua's answer), the ampersand can have special meaning in Oracle SQLPlus. But that isn't SQL. It is a different language that has SQL syntax embedded in it.