It concatenates the first character value to the second character value.
It accepts only two parameters accept.
It returns the character data type.

Syntax :

CONCAT( Column1/Expr1, Column2/Expr2)

Examples :
1.
SELECT
'Oracle' String1,
'Corporation' String2,
CONCAT('Oracle','Corporation') Concatenated string
FROM DUAL;

2.
SELECT Ename, Job, CONCAT(Ename, Job) Concat
FROM Emp
WHERE Deptno= 10;

3.
SELECT
CONCAT('The Employee Name is', INITCAP(Ename)) Info
FROM Emp
WHERE Deptno IN(10,30);

4.
SELECT
CONCAT(CONCAT(INITCAP(Ename),'is a '), Job) Job
FROM Emp
WHERE Deptno IN(10,20);