What is the logic behind how placeholders interact with expressions? I'm using DBD::SQLite and DBIx::Simple. I have an integer column called 'position' in my database: While this

$db->query( 
'SELECT * from thistable WHERE position <= ?', 
$position )->flat()
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works correctly, this doesn't:

$db->query( 
'SELECT * from thistable WHERE position - 1 <= ?',
$position )->flat();
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Could someone enlighten me, please?
Update: The data is just integers like

235
163
163
415
415
306
415
235
270
...

This returns 9 values of 'position':

$position = 500;

$db->query( 
'SELECT position from thistable WHERE position <= ?', 
$position )->flat()
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This returns 71,828 values of 'position', ie all the rows in the table: Note that the answer should be the same, 9 matching rows.

$position = 500;

$db->query( 
'SELECT position from thistable WHERE (position-1+1) <= ?', 
$position )->flat()
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Placeholders on the LHS This works, though:

$db->query( 
"SELECT position from thistable WHERE (position- ?) <= 500", 1 )->flat
+()
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And finally, I've tried DBI directly instead of DBIx::Simple, and still see this. (thanks to virtualsue for comments on making this more informative)