title: How to check a value in a SQLite column is NULL or not with C API?
body: <p>I'm using SQLite with C API.
  On C API, I can check the result value of a column with <code>sqlite3_column_*</code> functions. the problem is there is no function for the case of the value is <code>NULL</code>. Of course, I can check the value with <code>sqlite3_column_bytes</code> function, but it can cause conversion, and I want to avoid conversion at all.</p>
  
  <p>How can I check the value at a column of a row is NULL or not?</p>