Concatenation Operator in oracle is used to Concatenate two strings values. The concatenation in oracle can be done using the CONCAT() keyword. Also, concatenation can be done by using the '||' symbol.
Syntax
CONCAT( string1, string2);
Example
we have a Stu table as shown below:
1. CONCAT TWO COLUMNS
Now, we want concat Name and Subject column together. Follow the code for the same:
select CONCAT(name,Subject)from Stu;
Output

2. CONCAT MORE THAN TWO COLUMNS
We, want to contact Name, Subject, and Section Columns. Follow the code for the same:
select CONCAT(CONCAT(name,Subject),Section)from Stu;
OR
select name||Subject||Section from Stu;
NOTE: We cannot Concat 3 columns altogether. Therefore, we use the nest concat method to concatenate more than 2 columns.
Output 1
Output 2