PLSENULL

Plsenull scans PL/SQL source code looking for attempts to test for 
equality (or inequality) to NULL.  Synopsis:

	plsenull [filename]

Plsenull reads the specified file, or standard input if no file is
specified.

Specifically, plsenull looks for "=", "!=", or "<>" followed by NULL,
or vice versa.  For example:

	if emp_id = null then
		set_error( "No employee id" );
	end if;

	if dept_id != null then
		dept_name := get_dept_name( dept_id );
	end if;

Such code is legal PL/SQL but it's almost certainly a mistake, since nothing
can ever be equal to NULL.  If you're like me, you sometimes code this kind
of test through carelessness.  With plsenull you can quickly find and correct
such a blunder.

Whenever it finds such a construct, plsenull writes a message to standard
error, reporting the line number and column number where it occurred.

You can perform a similar search with a tool like grep, but grep can be
confused by various syntactic complications:


1. Differences in case: null, NULL, Null, nuLL, etc.

2. Assignments of NULL, as in "emp_id := NULL;"

3. Identifiers starting with "NULL", such as NULL_DEPARTMENT

4. The presence of tabs, line feeds, or comments between the equals (or
   not-equals) sign and the NULL

5. The occurrence of " = NULL;" or the like in comments or string literals


By careful use of grep you can reduce these problems, but you can't
eliminate them.  By contrast, plsenull will reliably detect the offending
code despite these complications.