Concatenation in SQL, Using For XML PATH(), Concatenate more than one

Some times it is required to concatenate more no of rows into one single filed separated by commas. There are some options for that like we can write our own UDF for that, in sql server built in COALESCE function is there with this function we can achieve it. But some time need is different or we want to achieve it in different way then there is another option that I am going to explain using FOR XML PATH().