squatpuke
Premium
join:2004-04-15
Flagstaff, AZ | Null Vs. Empty
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If a database field is originally NULL...then data is added....then removed....is the field NULL again...
What is the difference between NULL and Once Filled/Now Empty....
Thanks...
(btw...TSql) |
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jayco437
Premium
join:2001-08-11
Lincoln, NE
 ·Windstream
| said by squatpuke  :. If a database field is originally NULL...then data is added....then removed....is the field NULL again... I would imagine it could vary between databases, but my general thought is no it would not be NULL unless you explicitly set it to NULL, versus setting it to a blank string.
said by squatpuke :. What is the difference between NULL and Once Filled/Now Empty.... NULL is usually a default value for a field that doesn't require a value. Depending on the database, you could set default to an empty string instead of NULL. You could also programmatically set a field to NULL when it has been emptied of data, thus eliminating the ambiguity between NULL and and an empty string. |
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McSummation
Mmmm, Zeebas Are Tastee.
Premium,MVM
join:2003-08-13
Round Rock, TX
·AT&T Southwest
| reply to squatpuke
jayco437 did a good job of explaining the difference.
Another way to look at it is: a NULL field (can be any field, not just strings) has nothing stored in it. However, an "empty string" has a value, a "zero length" string. |
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Code_Iain
join:2006-10-09
Clifton Park, NY
1 edit | reply to squatpuke
Both other posters are correct with what they said, but just to give you an additional warning when working with both,
NULL represents the absence of a value and '' (empty string) is a value, so for example if your table has a unique index on a column, multiple rows can have that column set to NULL, but only 1 can be set to ''. |
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teddy
join:2002-02-20
Kingston, ON | reply to squatpuke
Just like to chip in, Oracle treats null and '' both as null. A pain sometimes, really.
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»www.chemicalfusion.net |
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Tenar
join:2008-01-02
Midland, ON | reply to squatpuke
Just don't set your database fields to 'NULL' (the string) LOL I've seen that. =P |
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