title: in sql server what is the difference between user_type_id and system_type_id in sys.types
body: <p>What is the difference between user_type_id and system_type_id in the view of sys.types in sql server?</p>
  
  <p>I want to inner join sys.columns with sys.types to get the data types of columns in a user table, but these two views both have two fields user_type_id and system_type_id, which one should be used?</p>