In case we’ve forgotten or have never come across inline table-valued functions before, we’ll start with a quick explanation of what they are.
Taking the definition of what a user defined function (UDF) is from Books Online, an inline table-valued function (iTVF) is a table expression that can accept parameters, perform an action and provide as its return value, a table. The definition of an iTVF is permanently stored as a database object, similar to a view would.
The syntax to create an iTVF from Books Online (BOL) can be found here and is as follows:
CREATE [ OR ALTER