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Problem with Check Constraints

P: n/a
RAD
I am working with an evaluation copy of SQL Server 2000 for the first
time; my DB experience lies with MS Access.

I have a simple table in SQL Server (tblCompany) that has a field
called "Ticker." When new company stock tickers (i.e., MSFT for
Microsoft) are entered into the field, I'd like them in all
caps--whether the user types msft, Msft, MsFt, etc. In Access, this
was easy--simply set the Format to ">" in table design view.

In SQL Server Design Table view, I've clicked on "Manage Constraints"
and put the following code in that I found elsewhere:

([Ticker] = upper([Ticker]))

I then checked all three boxes below: "Check existing data on
creation," "Enforce constraint for replication," and "Enforce
constraint for INSERTs and UPDATEs." The first one, "Check existing
data..." is checked as I've already entered in some data in the field
in lowercase to see if the check constraint would go back and change
it to Upper Case--this because I'm wanting to ultimately migrate a
table from Access to SQL Server and ensure that all Tickers are in
Upper Case.

I'm able to do this and then save the table design with changes; but
every time, I then go and look at the table data to see if the check
constraint was applied, and each time it is not; then, I go back to
"Manage Constraints" and find that the "Check existing data..." box is
unchecked. I've gone through this SEVERAL times.

Hoping this is something simple. Apologize for my "newbieness." I've
got a "For Dummies" book in front of me as well as numerous Internet
windows open, trying to figure this out. Have checked books online on
the MSFT site as well to no avail.

Thanks in advance--

RAD
Jul 20 '05 #1
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3 Replies


P: n/a
A constraint enforces data integrity rules but does not change existing or
newly inserted data. You need to cleanup your data and then add the
constraint to only permit uppercase values going forward.

If you want to automatically change values to upper case as they are entered
on the server side, you'll need to do this in a trigger. IMHO, this task is
better done in application code and let the database just enforce the data
integrity rule.

I don't know the details of the constraint you are adding but be aware that
case sensitivity is determined by collations in SQL 2000. The default
collation is case insensitive so you'll need to override the default
case-insensitive compare in your constraint. The example script below will
correct existing data and add a check constraint to ensure only upper case
values are allowed.

UPDATE Company
SET Ticker = UPPER('Ticker')
GO

ALTER TABLE Company
ADD CONSTRAINT CK_Ticker
CHECK (Ticker COLLATE SQL_Latin1_General_Cp1_CS_AS = UPPER(Ticker))
GO

On a side note, be aware that Hungarian notation (e.g. 'tbl' prefixes) are
frowned upon in client-server database design. The underlying database
implementation (table or view) should be transparent to database users.

--
Hope this helps.

Dan Guzman
SQL Server MVP

"RAD" <rd********@nyc.rr.com> wrote in message
news:d4*************************@posting.google.co m...
I am working with an evaluation copy of SQL Server 2000 for the first
time; my DB experience lies with MS Access.

I have a simple table in SQL Server (tblCompany) that has a field
called "Ticker." When new company stock tickers (i.e., MSFT for
Microsoft) are entered into the field, I'd like them in all
caps--whether the user types msft, Msft, MsFt, etc. In Access, this
was easy--simply set the Format to ">" in table design view.

In SQL Server Design Table view, I've clicked on "Manage Constraints"
and put the following code in that I found elsewhere:

([Ticker] = upper([Ticker]))

I then checked all three boxes below: "Check existing data on
creation," "Enforce constraint for replication," and "Enforce
constraint for INSERTs and UPDATEs." The first one, "Check existing
data..." is checked as I've already entered in some data in the field
in lowercase to see if the check constraint would go back and change
it to Upper Case--this because I'm wanting to ultimately migrate a
table from Access to SQL Server and ensure that all Tickers are in
Upper Case.

I'm able to do this and then save the table design with changes; but
every time, I then go and look at the table data to see if the check
constraint was applied, and each time it is not; then, I go back to
"Manage Constraints" and find that the "Check existing data..." box is
unchecked. I've gone through this SEVERAL times.

Hoping this is something simple. Apologize for my "newbieness." I've
got a "For Dummies" book in front of me as well as numerous Internet
windows open, trying to figure this out. Have checked books online on
the MSFT site as well to no avail.

Thanks in advance--

RAD

Jul 20 '05 #2

P: n/a
On 25 Jan 2004 10:17:18 -0800, rd********@nyc.rr.com (RAD) wrote:
I am working with an evaluation copy of SQL Server 2000 for the first
time; my DB experience lies with MS Access.

I have a simple table in SQL Server (tblCompany) that has a field
called "Ticker." When new company stock tickers (i.e., MSFT for
Microsoft) are entered into the field, I'd like them in all
caps--whether the user types msft, Msft, MsFt, etc. In Access, this
was easy--simply set the Format to ">" in table design view.

In SQL Server Design Table view, I've clicked on "Manage Constraints"
and put the following code in that I found elsewhere:

([Ticker] = upper([Ticker]))

I then checked all three boxes below: "Check existing data on
creation," "Enforce constraint for replication," and "Enforce
constraint for INSERTs and UPDATEs." The first one, "Check existing
data..." is checked as I've already entered in some data in the field
in lowercase to see if the check constraint would go back and change
it to Upper Case--this because I'm wanting to ultimately migrate a
table from Access to SQL Server and ensure that all Tickers are in
Upper Case.

I'm able to do this and then save the table design with changes; but
every time, I then go and look at the table data to see if the check
constraint was applied, and each time it is not; then, I go back to
"Manage Constraints" and find that the "Check existing data..." box is
unchecked. I've gone through this SEVERAL times.

Hoping this is something simple. Apologize for my "newbieness." I've
got a "For Dummies" book in front of me as well as numerous Internet
windows open, trying to figure this out. Have checked books online on
the MSFT site as well to no avail.

Thanks in advance--

RAD

That doesn't work, as can be shown with

select ticker from tblCompany where ticker = 'MSFT'

Your row will be returned regardless of the case of the data.

this may be something that can be set at the database level,
alternatively use a trigger to uppercase the data.

Something like;

create trigger instblCompany
on tblCompany
instead of insert
as
insert into tblCompany
select upper(ticker), all other columns
from inserted
Jul 20 '05 #3

P: n/a
RAD
Thanks both Dan and Lyndon--I'll give it a whirl.

RAD
Jul 20 '05 #4

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