I think the other commenters clarified it all, but I thought I'd add a little more.
Try this variant, with the variable x intentionally undefined.
write (1=0) && (x = 0)
0
Since 1=0 is 0, you don't get an <UNDEFINED> for x, since the right-hand (x=0) expression is ignored, and the entire statement is 0. Now try this:
write 1=0 && x=0
1
which, as @Roger Merchberger showed, is really
write (((1=0) && x) = 0)
Since 1=0 is 0, you again don't get an <UNDEFINED> for x, since the x expression (only) is ignored, and the ((1=0) && x) expression is 0. Finally, 0=0 is 1.
Thanks for the thoughts! To clarify, I was primarily asking about where to install IRIS itself. Within the context of that question, it's always good to include information about directories for the other important stuff, such as Journals and databases, so thanks for that.







As @Yaron Munz and @Alexander Koblov correctly pointed out, you can use Embedded SQL or Dynamic SQL. You can also use Class Queries.
Using Embedded SQL, host variables in IRIS (:varname) can be inputs or outputs, just like host variables in SQL Server and Oracle, but without any DECLARE statement. Host variables used as inputs are automatically sanitized. Examples:
Dynamic SQL allows ? placeholders for inputs only instead of host variables, also automatically sanitized. Examples:
Dynamic SQL returns output values in the result set object it returns, which you can access and copy into variables. Examples:
Class queries use host variables (:varname) for inputs (like Embedded SQL), and return output values in the result set object (like Dynamic SQL).