Hi,
I have question:
why such condition:
foofield not like '%bar%'
where foofield is varchar
returns false (or rather even ignore row) on record where foofield is null
but
returns true on records where foofield is '' (empty string)
regards
Robert
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If you are experienced in Oracle, this might be confusing since Oracle
treats empty string and NULL as being the same. On Mon, 13 Oct 2003, Robert Partyka wrote:
why such condition:
foofield not like '%bar%'
where foofield is varchar
returns false (or rather even ignore row) on record where foofield is
null
Actually, it probably returns unknown(NULL) on such records.
NULL LIKE '%bar%' is unknown, so
NULL NOT LIKE '%bar%' is also unknown.
This is because NULL isn't the same as empty string, nor is it the
absence of a value, but it's an unknown value.
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http://archives.postgresql.org
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TIP 6: Have you searched our list archives? http://archives.postgresql.org
Robert Partyka wrote: Hi,
I have question:
why such condition:
foofield not like '%bar%'
where foofield is varchar
returns false (or rather even ignore row) on record where foofield is null
but
returns true on records where foofield is '' (empty string)
SQL specifications.
Empty string and NULL are two different thinks.
Regards
Gaetano Mendola
On Mon, 13 Oct 2003, Robert Partyka wrote: why such condition:
foofield not like '%bar%'
where foofield is varchar
returns false (or rather even ignore row) on record where foofield is
null
Actually, it probably returns unknown(NULL) on such records.
NULL LIKE '%bar%' is unknown, so
NULL NOT LIKE '%bar%' is also unknown.
This is because NULL isn't the same as empty string, nor is it the absence
of a value, but it's an unknown value.
---------------------------(end of broadcast)---------------------------
TIP 6: Have you searched our list archives? http://archives.postgresql.org
If you are experienced in Oracle, this might be confusing since Oracle
treats empty string and NULL as being the same. On Mon, 13 Oct 2003, Robert Partyka wrote:
why such condition:
foofield not like '%bar%'
where foofield is varchar
returns false (or rather even ignore row) on record where foofield is
null
Actually, it probably returns unknown(NULL) on such records.
NULL LIKE '%bar%' is unknown, so
NULL NOT LIKE '%bar%' is also unknown.
This is because NULL isn't the same as empty string, nor is it the
absence of a value, but it's an unknown value.
---------------------------(end of broadcast)---------------------------
TIP 6: Have you searched our list archives?
http://archives.postgresql.org
---------------------------(end of broadcast)---------------------------
TIP 6: Have you searched our list archives? http://archives.postgresql.org vh*****@inreach.com wrote: If you are experienced in Oracle, this might be confusing since Oracle
treats empty string and NULL as being the same.
Really? I don't believe it.
Regards
Gaetano Mendola
Gaetano Mendola wrote: vh*****@inreach.com wrote:
If you are experienced in Oracle, this might be confusing since Oracle
treats empty string and NULL as being the same.
Really? I don't believe it.
It is insane, but true.
Mike Mascari ma*****@mascari.com
---------------------------(end of broadcast)---------------------------
TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faqs/FAQ.html
Mike Mascari <ma*****@mascari.com> writes: Gaetano Mendola wrote:
vh*****@inreach.com wrote:
If you are experienced in Oracle, this might be confusing since Oracle
treats empty string and NULL as being the same.
Really? I don't believe it.
It is insane, but true.
Uh, yeah, but I think that results in the same behaviour for the case at hand.
ie on oracle this is still holds:
NULL LIKE '%foo%' => NULL
The idiocy is that Oracle does this:
'' LIKE '%foo%' => NULL
because it treats '' as if you had NULL, ie, equivalent to the example above.
--
greg
---------------------------(end of broadcast)---------------------------
TIP 6: Have you searched our list archives? http://archives.postgresql.org vh*****@inreach.com wrote: If you are experienced in Oracle, this might be confusing since Oracle
treats empty string and NULL as being the same.
Really? I don't believe it.
Regards
Gaetano Mendola
Gaetano Mendola wrote: vh*****@inreach.com wrote:
If you are experienced in Oracle, this might be confusing since Oracle
treats empty string and NULL as being the same.
Really? I don't believe it.
It is insane, but true.
Mike Mascari ma*****@mascari.com
---------------------------(end of broadcast)---------------------------
TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faqs/FAQ.html
Mike Mascari <ma*****@mascari.com> writes: Gaetano Mendola wrote:
vh*****@inreach.com wrote:
If you are experienced in Oracle, this might be confusing since Oracle
treats empty string and NULL as being the same.
Really? I don't believe it.
It is insane, but true.
Uh, yeah, but I think that results in the same behaviour for the case at hand.
ie on oracle this is still holds:
NULL LIKE '%foo%' => NULL
The idiocy is that Oracle does this:
'' LIKE '%foo%' => NULL
because it treats '' as if you had NULL, ie, equivalent to the example above.
--
greg
---------------------------(end of broadcast)---------------------------
TIP 6: Have you searched our list archives? http://archives.postgresql.org This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
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