What is the best way to convert an int or null to boolean value in an SQL query?

Question

What is the best way to convert an int or null to boolean value in an SQL query, such that:

• Any non-null value is TRUE in the results
• Any

Answer 1

In Oracle, assuming you use 0 for false and 1 for true:-

SELECT DECODE( col, NULL, 0, 1) FROM ...

You can also write this using the CASE syntax, but the above is idiomatic in Oracle. DECODE is a bit like a switch/case; if col is NULL then 0 is returned, else 1.