title: Why does no database fully support ANSI or ISO SQL standards?
body: <p>If I were designing a oil refinery, I wouldn't expect that materials from different vendors would not comply with published standards in subtle yet important ways.  Pipework, valves and other components from one supplier would come with flanges and wall thicknesses to ANSI standards, as would the same parts from any other supplier.  Interoperability and system safety is therefore assured.</p>
  
  <p>Why then are the common databases so choosy about which parts of the standards they adhere to, and why have no 100% standards-compliant systems come to the fore?  Are the standards 'broken', lacking in scope or too difficult to design for?</p>
  
  <p>Taking this to conclusion; what is the point of ANSI (or ISO) defining standards for SQL?</p>
  
  <p>Edit: <a href="http://troels.arvin.dk/db/rdbms/" rel="noreferrer">List of implementation differences between common databases</a></p>