nULL OR nOT?
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The databases in question used VB6 for the front-end? (Zero is common for extremely low values of null in VB6). Primary reason that I don't like to use 0 for a key value and start from one, don't want to break anything. Now, as far as not null goes, I prefer the fourth normal form in cases you have described. I will leave the understanding as an exercise for the reader.
Need custom software developed? I do custom programming based primarily on MS tools with an emphasis on C# development and consulting. "And they, since they Were not the one dead, turned to their affairs" -- Robert Frost "All users always want Excel" --Ennis Lynch
Ennis Ray Lynch, Jr. wrote:
The databases in question used VB6 for the front-end?
Interestingly in this case the OLD platform was VB6 - and teh new Db was designed by those old VB programmers - so you're right, that could well be the reason.
Ennis Ray Lynch, Jr. wrote:
I prefer the fourth normal form in cases you have described
our database is, unfortunately, not normal in any way ;) It falls short of 3NF in many areas already!
MVVM # - I did it My Way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
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_Maxxx_ wrote:
I've come across a practice in more than one company where one or more develpers insit on not using null values in the database.
So at best they are ignorant.
_Maxxx_ wrote:
The argument I get is that "the customer does have an address, but we just don't know what it is yet."
The database is a persistent store - not a god. It "models" the data objects. And obviously if they want "We don't know what it is" then that is exactly what they should put in the database.
_Maxxx_ wrote:
but am willing to change my view if anyone can give a sound reason for any of this garbage.
One reason of course is that they do not in fact understand what null is. It confuses them. So a "sound" reason would be that you don't want to confuse them.
jschell wrote:
One reason of course is that they do not in fact understand what null is. It confuses them. So a "sound" reason would be that you don't want to confuse them.
NOOOOOooooo! That is certainly not a sound reason for using bad practices - it is sound reason for education!
MVVM # - I did it My Way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
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I've come across a practice in more than one company where one or more develpers insit on not using null values in the database. So, for example, if a customer address is unknown, the AddressId on the Customer table will have a value of (for example) zero - and the Address table will be pre-populated with a record with an Id of zero and (usually) empty string or zero values in the other columns. I've also come across the situation where, rather than having a null value in a 'sold price' column, the value of zero represents an unsold item. Putting aside my feelings (that these are weak-minded imbeciles who shouldn't be allowed near a database) do any of you subscribe to this theory? What's wrong with a null value which tells you explicitly "The customer has no address" or "This item has no price" The argument I get is that "the customer does have an address, but we just don't know what it is yet." I put it down to FUD factors - but am willing to change my view if anyone can give a sound reason for any of this garbage.
MVVM # - I did it My Way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
I like nulls; I don't like "magic values". Disallowing nulls is not a solution to the problem.
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I've come across a practice in more than one company where one or more develpers insit on not using null values in the database. So, for example, if a customer address is unknown, the AddressId on the Customer table will have a value of (for example) zero - and the Address table will be pre-populated with a record with an Id of zero and (usually) empty string or zero values in the other columns. I've also come across the situation where, rather than having a null value in a 'sold price' column, the value of zero represents an unsold item. Putting aside my feelings (that these are weak-minded imbeciles who shouldn't be allowed near a database) do any of you subscribe to this theory? What's wrong with a null value which tells you explicitly "The customer has no address" or "This item has no price" The argument I get is that "the customer does have an address, but we just don't know what it is yet." I put it down to FUD factors - but am willing to change my view if anyone can give a sound reason for any of this garbage.
MVVM # - I did it My Way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
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I've come across a practice in more than one company where one or more develpers insit on not using null values in the database. So, for example, if a customer address is unknown, the AddressId on the Customer table will have a value of (for example) zero - and the Address table will be pre-populated with a record with an Id of zero and (usually) empty string or zero values in the other columns. I've also come across the situation where, rather than having a null value in a 'sold price' column, the value of zero represents an unsold item. Putting aside my feelings (that these are weak-minded imbeciles who shouldn't be allowed near a database) do any of you subscribe to this theory? What's wrong with a null value which tells you explicitly "The customer has no address" or "This item has no price" The argument I get is that "the customer does have an address, but we just don't know what it is yet." I put it down to FUD factors - but am willing to change my view if anyone can give a sound reason for any of this garbage.
MVVM # - I did it My Way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
Is it possible they have simply read or heard that nulls are bad and so eradicate them with defaut values without understanding the database principles behind the statement? (I regularly use nulls in database design, normalising every last one away is rarely a worth it). Greg
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d@nish wrote:
So, when exactly should I drink coffee?
At 8:50 - just before your scrum meeting. (I generally drink more tea than coffee just to reduce my caffeine and calorie intake - I drink earl gray tea, black nothing added) You do have a scrum meeting with yourself, don't you?
MVVM # - I did it My Way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
Darjeeling, black, then attend to correspondence. The coffee comes mid morning when the code starts happening. Lucky enough to have an espresso machine at the office, so it's usually a cappuccino for me :cool:
-- For a moment, nothing happened. Then, after a second or so, nothing continued to happen --
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I've come across a practice in more than one company where one or more develpers insit on not using null values in the database. So, for example, if a customer address is unknown, the AddressId on the Customer table will have a value of (for example) zero - and the Address table will be pre-populated with a record with an Id of zero and (usually) empty string or zero values in the other columns. I've also come across the situation where, rather than having a null value in a 'sold price' column, the value of zero represents an unsold item. Putting aside my feelings (that these are weak-minded imbeciles who shouldn't be allowed near a database) do any of you subscribe to this theory? What's wrong with a null value which tells you explicitly "The customer has no address" or "This item has no price" The argument I get is that "the customer does have an address, but we just don't know what it is yet." I put it down to FUD factors - but am willing to change my view if anyone can give a sound reason for any of this garbage.
MVVM # - I did it My Way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
Yes, your example is FUD tactic for wrong practice. NULL is standard, my counter questions for those programmers is: "How do you handle three state logic and do you enforce "standards of yours" across all of your projects?"
Mislim, dakle jeo sam.
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I've come across a practice in more than one company where one or more develpers insit on not using null values in the database. So, for example, if a customer address is unknown, the AddressId on the Customer table will have a value of (for example) zero - and the Address table will be pre-populated with a record with an Id of zero and (usually) empty string or zero values in the other columns. I've also come across the situation where, rather than having a null value in a 'sold price' column, the value of zero represents an unsold item. Putting aside my feelings (that these are weak-minded imbeciles who shouldn't be allowed near a database) do any of you subscribe to this theory? What's wrong with a null value which tells you explicitly "The customer has no address" or "This item has no price" The argument I get is that "the customer does have an address, but we just don't know what it is yet." I put it down to FUD factors - but am willing to change my view if anyone can give a sound reason for any of this garbage.
MVVM # - I did it My Way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
The main reason for doing this, especially on FK's, is that you don't have to worry about what kind of join you're doing. If you have nulls, you need to usually use an outer join rather than a full join or an inner join. Otherwise, it's sort of a semantic difference to use 0 instead of a null, but that can also be really dangerous. Null means something which is different from zero, or any other value.
_Maxxx_ wrote:
but am willing to change my view if anyone can give a sound reason for any of this garbage.
My reason regarding the joins should be moot - any decent SQL generator should know to use the correct join when dealing with nullable FK's. On the other hand, people are lazy. Not a good enough reason to adopt their policies, IMO. Marc
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I've come across a practice in more than one company where one or more develpers insit on not using null values in the database. So, for example, if a customer address is unknown, the AddressId on the Customer table will have a value of (for example) zero - and the Address table will be pre-populated with a record with an Id of zero and (usually) empty string or zero values in the other columns. I've also come across the situation where, rather than having a null value in a 'sold price' column, the value of zero represents an unsold item. Putting aside my feelings (that these are weak-minded imbeciles who shouldn't be allowed near a database) do any of you subscribe to this theory? What's wrong with a null value which tells you explicitly "The customer has no address" or "This item has no price" The argument I get is that "the customer does have an address, but we just don't know what it is yet." I put it down to FUD factors - but am willing to change my view if anyone can give a sound reason for any of this garbage.
MVVM # - I did it My Way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
NULL is not indexed use NULL in arithmetic, string, logical and others operations is incorrect its use is the result of a incorrect designing database.
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I am against using nulls in the database because it means introducing 3 valued logic, which is known to be bad. The behavior of SELECT and conditions when nulls are involved is too complicated.
Rosenne wrote:
it means introducing 3 valued logic, which is known to be bad.
Known by whom? If there are three logical values then you need to use 3 valued logic!
Rosenne wrote:
The behavior of SELECT and conditions when nulls are involved is too complicated.
Because you don't understand it is not a good reason for not using it - it simply means you should not be designing databases.
MVVM # - I did it My Way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
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NULL is not indexed use NULL in arithmetic, string, logical and others operations is incorrect its use is the result of a incorrect designing database.
Igor Kovalev wrote:
NULL is not indexed
In which database? My understanding is that oracle while not actually indexing nulls, will still utilise an index on a nullable column. And I think SQL Server does index nulls.
Igor Kovalev wrote:
use NULL in arithmetic, string, logical and others operations is incorrect
Interesting statement? says who? Incorrect why, in what way?
Igor Kovalev wrote:
its use is the result of a incorrect designing database.
so. pray tell, why do databases even HAVE a NULL? If it's so incorrect to use it, surely databases sholdn't support it?
MVVM # - I did it My Way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
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Igor Kovalev wrote:
NULL is not indexed
In which database? My understanding is that oracle while not actually indexing nulls, will still utilise an index on a nullable column. And I think SQL Server does index nulls.
Igor Kovalev wrote:
use NULL in arithmetic, string, logical and others operations is incorrect
Interesting statement? says who? Incorrect why, in what way?
Igor Kovalev wrote:
its use is the result of a incorrect designing database.
so. pray tell, why do databases even HAVE a NULL? If it's so incorrect to use it, surely databases sholdn't support it?
MVVM # - I did it My Way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
1)SELECT on the table that has a value of NULL will result in FULL SCAN 2)try null = null or null + 4 3)look for database normalization
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_Maxxx_ wrote:
The argument I get is that "the customer does have an address, but we just don't know what it is yet."
Which is actually correct, and quite a nice way of stating a technical point in plain language. The empty string represents an unset address, whereas null indicates that there is no address. Unsurprisingly, most people don't think "does a field have a value or not?", they think "do we know the address?". Only developers are brought up to detach data from reality, and DBAs don't have to be developers, but they do have to know their data.
I wanna be a eunuchs developer! Pass me a bread knife!
There is something inherently wrong with a product that has not been assigned a price being defaulted to zero. I actually had a customer order his "free" device because it showed up in the catalog with a price of zero. If it were null, it would have missed the query. Some fields should allow null, some must allow null and yet others must not.
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1)SELECT on the table that has a value of NULL will result in FULL SCAN 2)try null = null or null + 4 3)look for database normalization
1. Not true - check your facts. 2. Sorry - I see what you mean - yes, certainly it is incorrect to try to do arithmetic on 'nothing' so, let's say you have a numeric column on your table and, instead of using null to represent it not having a value, you use zero. Now, what is the average of that column? You can't tell which rows to count because you are not differentiating between rows who's value is zero and rows that do not have a value. 3. Mate, I've been doing database normalisation longer than you've been alive; if you have a point to make, make it! you said "its use is the result of a incorrect designing database." So you are saying you should not design a database to have null columns? Unless I am misunderstanding what you are saying, then you imply that the NULL 'value' is not necessary!
MVVM # - I did it My Way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
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1. Not true - check your facts. 2. Sorry - I see what you mean - yes, certainly it is incorrect to try to do arithmetic on 'nothing' so, let's say you have a numeric column on your table and, instead of using null to represent it not having a value, you use zero. Now, what is the average of that column? You can't tell which rows to count because you are not differentiating between rows who's value is zero and rows that do not have a value. 3. Mate, I've been doing database normalisation longer than you've been alive; if you have a point to make, make it! you said "its use is the result of a incorrect designing database." So you are saying you should not design a database to have null columns? Unless I am misunderstanding what you are saying, then you imply that the NULL 'value' is not necessary!
MVVM # - I did it My Way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
I ve been doing database normalisation longer than you've been alive;" why you discuss about this issue with me? The use of NULL is true for Oratsle but not true for all DB. In another DB empty string is it not NULL
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I ve been doing database normalisation longer than you've been alive;" why you discuss about this issue with me? The use of NULL is true for Oratsle but not true for all DB. In another DB empty string is it not NULL
Igor Kovalev wrote:
why you discuss about this issue with me?
Because you are stating as facts things that are not true, and you are responding to my initial question about the use of nulls
Igor Kovalev wrote:
The use of NULL is true for Oratsle but not true for all DB.
Oracle I assume you mean? And you mean that Nulls are not indexed in Oracle? Yes, I understand that that is true. I also understand it is not true for all databases.
Igor Kovalev wrote:
In another DB empty string is it not NULL
sorry, I don't understand? Appreciate English probably is your 2nd language; I don't believe in any database an empty string is null. Null has a special meaning - i.e. 'there is no value'
MVVM # - I did it My Way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
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Igor Kovalev wrote:
why you discuss about this issue with me?
Because you are stating as facts things that are not true, and you are responding to my initial question about the use of nulls
Igor Kovalev wrote:
The use of NULL is true for Oratsle but not true for all DB.
Oracle I assume you mean? And you mean that Nulls are not indexed in Oracle? Yes, I understand that that is true. I also understand it is not true for all databases.
Igor Kovalev wrote:
In another DB empty string is it not NULL
sorry, I don't understand? Appreciate English probably is your 2nd language; I don't believe in any database an empty string is null. Null has a special meaning - i.e. 'there is no value'
MVVM # - I did it My Way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
yes it's my secondary language.
I am sorry for the misuse. about equals empty string and null...
https://db.apache.org/torque/torque-3.3/version-specific/database-howtos/oracle-howto.html
you'll be surprised -
I've come across a practice in more than one company where one or more develpers insit on not using null values in the database. So, for example, if a customer address is unknown, the AddressId on the Customer table will have a value of (for example) zero - and the Address table will be pre-populated with a record with an Id of zero and (usually) empty string or zero values in the other columns. I've also come across the situation where, rather than having a null value in a 'sold price' column, the value of zero represents an unsold item. Putting aside my feelings (that these are weak-minded imbeciles who shouldn't be allowed near a database) do any of you subscribe to this theory? What's wrong with a null value which tells you explicitly "The customer has no address" or "This item has no price" The argument I get is that "the customer does have an address, but we just don't know what it is yet." I put it down to FUD factors - but am willing to change my view if anyone can give a sound reason for any of this garbage.
MVVM # - I did it My Way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
RIGHT, sounds like some very old DBA's whose time is before Null became popular/sensible. An address, espicially if it is the first record, should not allow null; a person can have more than one address, so let the second/third,etc. allow nulls. Yes, I am having my tea. The front end issues can be resolved by checking for nulls in the stored proc CRUD's and sending error messages out instead of garbage; avoiding lot's of metadata on what the default values should be; today a zero, tomorrow an empty string. I use Null in all of my query's/procs, it is a must for any DBA or Programmer; consistancy that everyone can agree on. As long as your using it and checking for it, apps won't crash because of unkowns yet to be know and the database won't fill up with garbage, espicially ID's. I struggle all the time with poor app/database design, sigh, guess thats why we get the big bucks. Hang in there and don't let the bastards make you use MS Access, lol. ;)
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I've come across a practice in more than one company where one or more develpers insit on not using null values in the database. So, for example, if a customer address is unknown, the AddressId on the Customer table will have a value of (for example) zero - and the Address table will be pre-populated with a record with an Id of zero and (usually) empty string or zero values in the other columns. I've also come across the situation where, rather than having a null value in a 'sold price' column, the value of zero represents an unsold item. Putting aside my feelings (that these are weak-minded imbeciles who shouldn't be allowed near a database) do any of you subscribe to this theory? What's wrong with a null value which tells you explicitly "The customer has no address" or "This item has no price" The argument I get is that "the customer does have an address, but we just don't know what it is yet." I put it down to FUD factors - but am willing to change my view if anyone can give a sound reason for any of this garbage.
MVVM # - I did it My Way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
There's a ton of DB research on the subject. Read up on CJ Date and the third manifesto as they're what most of the "nulls are bad" papers are based off of. It has been a while since my database theory courses but the best reason I remember is dealing with joins. Since joining on a null value gets dropped from the resulting set, you may miss data. For instance you may think that you have 200 records in the database because some complicated join returned just 200 items but you're joining on a column with 100 nulls, thus you miss 100 records. Hence the idea that people should try to avoid nulls. That said if you reorganize the database to avoid that, you almost always have to do left outer joins or unions or some other crazy approach to get all the data anyway which reintroduces the nulls... So instead your DB people went the default value approach. It's actually clever as long as it's well documented that they did that.
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I've come across a practice in more than one company where one or more develpers insit on not using null values in the database. So, for example, if a customer address is unknown, the AddressId on the Customer table will have a value of (for example) zero - and the Address table will be pre-populated with a record with an Id of zero and (usually) empty string or zero values in the other columns. I've also come across the situation where, rather than having a null value in a 'sold price' column, the value of zero represents an unsold item. Putting aside my feelings (that these are weak-minded imbeciles who shouldn't be allowed near a database) do any of you subscribe to this theory? What's wrong with a null value which tells you explicitly "The customer has no address" or "This item has no price" The argument I get is that "the customer does have an address, but we just don't know what it is yet." I put it down to FUD factors - but am willing to change my view if anyone can give a sound reason for any of this garbage.
MVVM # - I did it My Way ___________________________________________ Man, you're a god. - walterhevedeich 26/05/2011 .\\axxx (That's an 'M')
I guess it depends on the application. I've run into more than my share of field errors where "invalid use of null" came up so I came to hate it. To me, an unitialized string is "", int is 0 etc. Having said that I can see uses for null, but having to test for it all the time can be a pain. If your GUI is written well, though, it should ensure that all appropriate initializations are made when creating a new record. I guess the fact that I've had to fix all these bad GUI's has driven my distaste of null. If the GUI is coded properly, null can be useful as a data validation.