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Check constraint question


2006-12-13 05:45:28 PM
delphi150
Hi.
How can i write check constraint witch can check somethink like this
1. table definition
CREATE Table XXX
(ID Integer Primary Key
Name VarChar(10),
CONSTRAINT UK_XXX__NAME UNIQUE(NAME)
)
and I'd check unique name but uppercase (not casesensitive unique)
i tray with this
Constraint CK_XXX__NAMEUQ CHECK(NOT EXISTS(SELECT * FROM XXX X WHERE
X.ID<>ID /*here is my problem how alias this*/ and Upper(X.NAME COLLATE
PXW_PLK)=Upper(NAME COLLATE PXW_PLK)))
X.NAME is the same for Interbase like NAME - i can't alias this field
(from record to check)
Please help.
I do not need trigger.
Karol Bieniaszewski
 
 

Re:Check constraint question

Hi i repost this question becaouse i get not answer on it in
borland.public.interbase.sql since 2006-12-13.
How can i write check constraint witch can check somethink like this
1. table definition
CREATE Table XXX
(ID Integer Primary Key
Name VarChar(10),
CONSTRAINT UK_XXX__NAME UNIQUE(NAME)
)
and I'd check unique name but uppercase (not casesensitive unique)
i tray with this
Constraint CK_XXX__NAMEUQ CHECK(NOT EXISTS(SELECT * FROM XXX X WHERE
X.ID<>ID /*here is my problem how alias this*/ and Upper(X.NAME COLLATE
PXW_PLK)=Upper(NAME COLLATE PXW_PLK)))
X.NAME is the same for Interbase like NAME - i can't alias this field
(from record to check)
Please help.
I do not need trigger.
Karol Bieniaszewski
 

Re:Check constraint question

Karol Bieniaszewski writes:
Quote
Hi i repost this question becaouse i get not answer on it in
borland.public.interbase.sql since 2006-12-13.

How can i write check constraint witch can check somethink like this

1. table definition
CREATE Table XXX
(ID Integer Primary Key
Name VarChar(10),
CONSTRAINT UK_XXX__NAME UNIQUE(NAME)
)

and I'd check unique name but uppercase (not casesensitive unique)

i tray with this

Constraint CK_XXX__NAMEUQ CHECK(NOT EXISTS(SELECT * FROM XXX X WHERE
X.ID<>ID /*here is my problem how alias this*/ and Upper(X.NAME COLLATE
PXW_PLK)=Upper(NAME COLLATE PXW_PLK)))

X.NAME is the same for Interbase like NAME - i can't alias this field
(from record to check)

Please help.
I do not need trigger.

Karol Bieniaszewski
Let me first try to restate your question and see if I understand what you
need.
You want to allow mixed case in the Name column but you want it to be unique
as if it were uppercase?
I would guess this is because you want your user to select by Name and have
it be unique.
You can not do this on the Name field. But, what I have done is create another
column Name2, which will have the Uppercase data from Name. I add a trigger
to automatically copy the Name data to Name2 as Uppercase when the data is
inserted (or updated). Name2, which is always uppercase, can have a unique
constraint on it. You can also search Name2, rather than Name, with the
Uppercase of any user request.
Patrick
 

Re:Check constraint question

Patrick Moloney writes:
Quote

You can not do this on the Name field.
Yes you can, as I already showed, but with the caveat that it will not use
an index.
--
Wayne Niddery - Winwright, Inc (www.winwright.ca)
"If there is any principle of the Constitution that more imperatively
calls for attachment than any other, it is the principle of free
thought - not free thought for those who agree with us, but freedom for
the thought that we hate." - Oliver Wendell Holmes
 

Re:Check constraint question

Użytkownik "Wayne Niddery [TeamB]" <XXXX@XXXXX.COM>napisa?w
wiadomości news:45aa4ddd$XXXX@XXXXX.COM...
Quote
Patrick Moloney writes:
>
>You can not do this on the Name field.

Yes you can, as I already showed, but with the caveat that it will not use
an index.

--
Wayne Niddery - Winwright, Inc (www.winwright.ca)
"If there is any principle of the Constitution that more imperatively
calls for attachment than any other, it is the principle of free
thought - not free thought for those who agree with us, but freedom for
the thought that we hate." - Oliver Wendell Holmes
thanks Wayne for answer on borland.public.delphi.database.general
i have there one more question.
Karol Bieniaszewski
 

Re:Check constraint question

"Wayne Niddery [TeamB]" writes:
Quote
Patrick Moloney writes:
>
>You can not do this on the Name field.

Yes you can, as I already showed, but with the caveat that it will not use
an index.

--
Wayne Niddery - Winwright, Inc (www.winwright.ca)
"If there is any principle of the Constitution that more imperatively
calls for attachment than any other, it is the principle of free
thought - not free thought for those who agree with us, but freedom for
the thought that we hate." - Oliver Wendell Holmes
Wayne,
Since your historical quotation is longer than your response, let me first
agree with that, and therefore with your solution, especially since the
question only asked about how to get the data in.
If one wants to get the data out however, it might be easier to store the
uppercase value in a separate column as I suggested. Processing mixed case
data as uppercase will require applying a function to the table values
whenever you want to use the data rather than simply accessessing the correct
record. Anyway, that is my free thought for today.
Patrick
 

Re:Check constraint question

Patrick Moloney writes:
Quote
If one wants to get the data out however, it might be easier to store
the uppercase value in a separate column as I suggested. Processing
mixed case data as uppercase will require applying a function to the
table values whenever you want to use the data rather than simply
accessessing the correct record. Anyway, that is my free thought for
today.
Typically it is only in *comparing* data that one needs it all uppercase, I
wouldn't expect, in most cases atr least, that one would want the data
returned to an application in uppercase. If so then it should be stored that
way in the first place.
--
Wayne Niddery - Winwright, Inc (www.winwright.ca)
"The legitimate powers of government extend to such acts only as are
injurious to others. But it does me no injury for my neighbor to say
there are twenty gods, or no God. It neither picks my pocket nor breaks
my leg." - Thomas Jefferson
 

Re:Check constraint question

Użytkownik "Wayne Niddery [TeamB]" <XXXX@XXXXX.COM>napisa?w
wiadomości news:45aba30b$XXXX@XXXXX.COM...
Quote
Patrick Moloney writes:
>If one wants to get the data out however, it might be easier to store
>the uppercase value in a separate column as I suggested. Processing
Storing data in separate column is mistake - and database grow up.
Quote
>mixed case data as uppercase will require applying a function to the
>table values whenever you want to use the data rather than simply
>accessessing the correct record. Anyway, that is my free thought for
>today.

Typically it is only in *comparing* data that one needs it all uppercase,
I wouldn't expect, in most cases atr least, that one would want the data
returned to an application in uppercase. If so then it should be stored
that way in the first place.

--
Wayne Niddery - Winwright, Inc (www.winwright.ca)
"The legitimate powers of government extend to such acts only as are
injurious to others. But it does me no injury for my neighbor to say
there are twenty gods, or no God. It neither picks my pocket nor breaks
my leg." - Thomas Jefferson
Yes i agree with you (Wayne Niddery)
this is only for comparing data and user get text what he/she previous
wrote.
Karol Bieniaszewski
 

Re:Check constraint question

Yes, the database will get bigger by storing the name twice. If it is a small
table (10-20 rows) it will not matter. But, the larger the table, the more
important it is to work efficiently. If the table is small, you can evaluate
every row in the table every time you want to use it. If the table is large,
you would rather be able to directly access the record you want. So, for
example, if this is a list of products and the user enters a sales order, you
want to be able to quickly check if the product code is valid. You can check
every record if you have 20 products, but if you have thousands, you need
different, more complicated code and you need to scan thousands of records.
And, you have to code that into every feature of your program. So, it depends
on what you need to do.
Patrick
 

Re:Check constraint question

"Karol Bieniaszewski" <XXXX@XXXXX.COM>writes:
Quote
How can i write check constraint witch can check somethink like this
1. table definition
CREATE Table XXX
(ID Integer Primary Key
Name VarChar(10),
CONSTRAINT UK_XXX__NAME UNIQUE(NAME)
)

and I'd check unique name but uppercase (not casesensitive unique)

i tray with this

Constraint CK_XXX__NAMEUQ CHECK(NOT EXISTS(SELECT * FROM XXX X WHERE
X.ID<>ID /*here is my problem how alias this*/ and Upper(X.NAME COLLATE
PXW_PLK)=Upper(NAME COLLATE PXW_PLK)))

X.NAME is the same for Interbase like NAME - i can't alias this field
(from record to check)


Please help.
I do not need trigger.
Aren't constraints enforced by triggers behind the scene anyways?
Be that as it may, why not use a COMPUTED BY column in Interbase - no
need for a trigger and you can have one the upper of the other.
With space overheads no longer being a major issue, there's nothing
wrong with using a shadow column.
Paul...
Quote
Karol Bieniaszewski
--
plinehan __at__ yahoo __dot__ __com__
XP Pro, SP 2,
Oracle, 10.2.0.1 (Express Edition)
Interbase 6.0.2.0;
When asking database related questions, please give other posters
some clues, like operating system, version of db being used and DDL.
The exact text and/or number of error messages is useful (!= "it didn't work!").
Thanks.
Furthermore, as a courtesy to those who spend
time analysing and attempting to help, please
do not top post.
 

Re:Check constraint question

Uzytkownik "Paul" <XXXX@XXXXX.COM>napisal w wiadomosci
Quote


"Karol Bieniaszewski" <XXXX@XXXXX.COM>writes:


>How can i write check constraint witch can check somethink like this

>1. table definition
>CREATE Table XXX
>(ID Integer Primary Key
>Name VarChar(10),
>CONSTRAINT UK_XXX__NAME UNIQUE(NAME)
>)
>
>and I'd check unique name but uppercase (not casesensitive unique)
>
>i tray with this
>
>Constraint CK_XXX__NAMEUQ CHECK(NOT EXISTS(SELECT * FROM XXX X WHERE
>X.ID<>ID /*here is my problem how alias this*/ and Upper(X.NAME COLLATE
>PXW_PLK)=Upper(NAME COLLATE PXW_PLK)))
>
>X.NAME is the same for Interbase like NAME - i can't alias this field
>(from record to check)
>
>
>Please help.
>I do not need trigger.



Aren't constraints enforced by triggers behind the scene anyways?


Be that as it may, why not use a COMPUTED BY column in Interbase - no
need for a trigger and you can have one the upper of the other.


With space overheads no longer being a major issue, there's nothing
wrong with using a shadow column.


Paul...

this is nice thing :) - I will try it.
thanks,
Karol Bieniaszewski