Does "WHERE 0=1" require a full table scan?

Hi,

a simple question: For a query like "SELECT * FROM table WHERE 0=1", does Oracle do a full table scan, or does it optimize the query away and return nothing without accessing the table?

The background for this question is, I'm writing a C++ function that takes a column name and a list of strings and creates a WHERE clause to search for these strings, like "column IN ('string 1','string 2',...). In case of an empty list I want to create a WHERE clause that matches nothing, and I'm pondering whether "WHERE 0=1" or "WHERE column!=column" would be better.

Thanks for your help
Wolfram Roesler Received on Fri Jan 30 2004 - 05:13:37 CST