On Wed, 1 Dec 2004, Brass Tilde wrote:
i've read the 'null handling' section and still not found the answer to
this
question:
why should
'select * from tbl where field=null'
be any different from
'select * from tbl where field isnull'
The short answer is "because it's different".
A longer answer would reference the SQL-92 standard, talking about how any
comparison involving null will resolve to false, including "null = null".
Null is defined to be not equal to anything, including null.
You *must* use "is null" to check for null, that's the way the SQL language
is implemented, and it's the way that all SQL-92 compliant implementations
are supposed to behave.
hmmm. that's a good answer, but from the docs:
"SQL As Understood By SQLite
The SQLite library understands most of the standard SQL language. But it does
omit some features while at the same time adding a few features of its own.
This document attempts to describe precisely what parts of the SQL language
SQLite does and does not support. A list of keywords is given at the end."
i guess what i'm driving at is that, given that sqlite is not sql-92
compliant, there seems to be good reason for this behaviour.
oh well. guess i'll live with it.
thanks for the response.
-a
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