title: Multi-use and use-Type field vs. A field per any use
body: <p>I have a table for some uses like this example:</p>
  
  <p>A table for objects named <code>tblObject</code> that needs to store some properties; So, I can use one of these solutions:</p>
  
  <ol>
  <li>Add a field for each property and with its own data type.</li>
  <li>Just add one field of foreign key that related to below model that in <code>tblObjProp</code> I need another field for storing variant values:</li>
  </ol>
  
  
  
  <pre><code>+-----------+         +------------+         +-------------+
  | tblObject | 1-----* | tblObjProp | *-----1 | tblProperty |
  +-----------+         +------------+         +-------------+
  </code></pre>
  
  <hr>
  
  <p>I think using this solutions is based on properties count, As I don't know the count, I need to have a reference like a recommendation in this site to identify that count or any other recommendation.  </p>
  
  <p>And also I need some recommendation for data type of <code>value</code> field in <code>tblObjProp</code> that in SQL I have <code>sql_variant</code> or <code>nvarchar(max)</code> or etc.</p>
  
  <p>If answers are related to RDBMS, I need that for <em>SQL Server 2012</em> and <em>Oracle 11g</em>.</p>
  
  <hr>
  
  <p>If I have a table like <code>Person</code> with columns <code>Id, FirstName, LastName, BirthDate, Comments, NID, ...</code> there is a choice for each column:</p>
  
  <ul>
  <li>Make it static in the <code>Person</code> table.</li>
  <li>Add it to <code>tblProperty</code>.</li>
  </ul>
  
  <p>That I want to know I should always select the second choice or for example for <code>Comments</code> or <code>NID</code> first choice is better?</p>