How to pass c# list into oracle procedure

I assume that you have two tables in your database, one called Persons and another called Relations, PersonID is a Foreign Key in the Relations table.

One approach is to create two stored procedures, one to store the person and one that stores the relations one by one.
From the first SP must return the primary key of the Persons table, and that variable is then used as a parameter together with the relation data into the second SP.
This way will require several transactions, but from an implementation point of view it is pretty clean.

Example

CREATE FUNCTION AddPerson(IN personID INT, IN personName VARCHAR(45)) RETURNS INT
BEGIN
    -- Do the insertion
    RETURN lastInsertedPersonID;
END

CREATE PROCDURE AddRelation(IN personID INT, IN relationID INT, IN relationType INT)
BEGIN
    -- Do the insertion
END

You could also serialize the object Person as XML, Examples of XML Serialization[^], and send into the SP as a string and then use XMLPARSE[^] inside the SP to extract the data.

This will require a loop for extracting the data, see LOOP Statements[^]

The advantage of the second method is that you will only have one transaction, but on the other hand the code will be more complex.