what exactly are you trying to do?
you want to store the value of the id session variable in a column of the petdata table right?
that column should be a foriegn key column your database, not the id column
dont set the store as column name to id, that will overwrite the users session variable when the record is inserted.
the users id should not be stored in the id column either.
you need another column to store the users id value in
in the insert record behavior, you select the column that will store the user id session variable in and click the lightning bolt next to value and select the id session variable.