CONCAT

    This will be used to combine two strings only.

    Syntax: concat (string1, string2)

    Ex:

         SQL> select concat('computer',' operator') from dual;

CONCAT('COMPUTER'

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computer operator

    If you want to combine more than two strings you have to use concatenation  

    operator(||).

         SQL> select 'how' || ' are' || ' you' from dual;

'HOW'||'ARE

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how are you