The constant '1' (of storage class TEXT) has no affinity, neither has the
constant 1 (of storage class INTEGER), nor the result of an expression - with
documented exceptions, notably CAST(<value> AS <type>).
Consider:
1 = '1'
-------
0
(1=1) = '1'
-----------
0
cast((1=1) as integer) = '1'
----------------------------
1
cast((1=1) as text) = '1'
-------------------------
1
(1=1) = cast('1' as integer)
----------------------------
1
(1=1) = cast('1' as text)
-------------------------
1
The first and last CAST() examples are particularly interesting. The CAST
doesn't change it's operand's storage class (argument is already in the target
storage class); it only sets an affinity, so the subsequent comparison is
prompted to convert the result on the *other* side of the equality operator.
-----Ursprüngliche Nachricht-----
Von: sqlite-users [mailto:[email protected]] Im
Auftrag von Jeffrey Mattox
Gesendet: Donnerstag, 26. Jänner 2017 11:03
An: SQLite mailing list <[email protected]>
Betreff: [sqlite] text/numeric comparison confusion
When used in a SELECT, I expect this comparison to be true (and it is):
( cast('25' as INTEGER) = 25 ) <--- true
But, why is this false:
( '25' = 25 ) <--- false?
and this is true:
( cast(25 as TEXT) = 25 ) <--- true
So, being that second comparison is false (why?), then why isn't the third
comparison also false?
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Gunter Hick
Software Engineer
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