When I select a fieldname in a db as a primary key this will keep the uniqueness of that fieldname, but how is that work when I select 2 fieldnames (in Enterprise Manager) and click on the Key it will mark them as my primary key, but I can insert duplicates values in either fieldname.
Can someone explain this to me.
Thanks
hi
am new to sql...i need to write a query ..it is like two teams can play more than 1 game but on different dates..
so if i create the table like this
Create Table Games( TeamName1 char(30),
2 numGoals1 int,
3 TeamName2 char(30),
4 numGoals2 int,
5 play_date char(10),
6 primary key(TeamName1,TeamName2,play_date),
7 Check(TeamName1!=TeamName2)
8 );
this violates the constraint if i give the two teams on the same date..how to give the condition such that it checks for the violation of condition if the team names are interchanged.. for eg
if i give the values as
Insert Into Games values('chelsea',1,'arsenal',2,'17-1-2000');
and
Insert Into Games values('arsenal',1,'chelsea',2,'17-1-2000');
the above should violate the constraint ..how to do it
Hello,
My company is upgrading one of our products; this involves some data migration and a question about existing indexes with uniqueness constraints has been raised. Here is the issue:
We have a database table with two particular columns that that we index with a uniqueness constraint. My question is: is the uniqueness constraint case sensitive?
For instance, if I have a database that is using a collation of SQL_Latin1_General_CP1_CS_AS. (case sensitive) and I insert data in these two columns as follows:
test
col2test
Test
col2test
would this uniqueness constraint be violated even though I'm using a case sensitive collation? I've done tests on this issue and I can't seem to insert this 2nd column; I'm just wanting to be certain that this is the case 100% of the time.
Thanks for your assistance,
Aaron
Hi,
Can anyone tell me the order in which uniqueness constraints on indexes are enforced vs. when triggers are executed ? I have a unique constraint on an index and a trigger on the column on which the same index has been created. When a row is inserted, the trigger checks if the value for that column already exists in the table - if not, it inserts the row as is, else it gets the max() val of the column (based on another key column) and increments it by one, then does the insert. Creating an index across the two works fine, but if I set the Unique Values property for the index, subsequent inserts bomb out - yet there aren't any duplicates in the final table, as the trigger ensures this. Anyone got any ideas on this? My deduction is that the uniqueness constraint gets enforced before the trigger gets executed, but at the same time this *seems* illogical, as the row has not been inserted into the table at the point where the trigger is executed.
Regards,
Jon Reade.
OK - maybe my Google-fu is off today but I'm trying to find out if using a sequence table will provide values that are as unique as the GUID is supposed to be.The reason is that I'm building a DW from the ground up (they won't let me expense my booze which I think is grossly unfair ) and rather than using GUID it ~seems~ like a sequence table would give better results. My concern is that the values won't be unique across tables.
View 9 Replies View RelatedHi,First of all my apologies if you have seen this mail already but I amre-sending as there were some initial problems.This query is related to defining indexes to be unique or not andconsequences thereof.Some documented facts that I am aware of include1. Defining uniqueness allows optimiser to create optimal plans egselect based on keys in such an index allows the optimiser to determineat most only one row will be returned2. Defining uniqueness ensures that rule (business/Primary key) isenforced, regradless of how the data is entered.We have many cases where non unique indexes are defined. The approach todate has been that even though we are aware of some of the benefitsoffered by defining uniqueness , we have chosen not to add keys to nonunique indexes such that they become unique. The primary reason for thiswas that we did not want to make the keys comprising the indexesunnecessarily large and therefore ensuing consequences when DMLstatements are performed.However, I have concerns that having highly duplicate indexes can haveperformance impacts , including deadlocking. I am also aware Sybase usedto store duplicate values in overflow pages and therefore there wereperformance consequences. Could SQL 2000 have the same behaviour ?Thanking you in advancePuvendran*** Sent via Developersdex http://www.developersdex.com ***Don't just participate in USENET...get rewarded for it!
View 1 Replies View RelatedSo, I have this idea of a database design I was hoping to get some input on.
I usually go through the process of creating a separate column for identity, like an auto-increment integer which serves as a context specific ID that easily can be passed around. However one of the short-comings I've come to realize is that the integer is just that, unique to the context and requires context information to make sense.
I'm pounding the idea of creating a separate table whose sole purpose is to provide global (database wide) unique IDs. As such each row in a table can still have an ID but instead of being tied to a specific context it will always make sense within the application. A foreign key constraint can ensure that and a relation.
Now, with a global ID which I can create FKs to, I don't have to create a separate table for relations between entities and can have relations through these global IDs and I think that's a good thing because if there are many relations between many entities they don't have to be defined more than once. There is also a single "hub" where all relations fit which will allow me to access most information through some relatively simple joins.
My concerns are performance and Linq to SQL implication. I'm worried that Linq to SQL might start pulling an excessive amount of data and I'm worried that the practicality of such a design might hurt the long running of the application development process.
But I'm surprisingly interested in what it could mean for a more ubiquitous view of data and tagging. Basically a way of any data to have relations to any other data through this yet simple design decision.
If you think this is a good idea or see no particular problem with, please let me know! If you think there's problems with my idea, please motivate your critic but do tell me what I should look out for, or if you know of any better approach to my idea of being able to look at the data through some more common mechanism (which applies to all tables and the entire database mostly from a programming perspective).
I want to make sure that usernames and folder names (that are stored in the database) are all unique when created by the admin through an admin control panel.
How would I code and use an Index to make sure that the 2 columns are unique?
I've looked at examples on the net but nothing is telling me how I can create an index through Enterprise Manager? Thanks
I want to make sure that usernames and folder names (that are stored in the database) are all unique when created by the admin through an admin control panel.
How would I code and use an Index to make sure that the 2 columns are unique?
I've looked at examples on the net but nothing is telling me how I can create an index through Enterprise Manager? Thanks :)
I"m trying to use a BULK INSERT command to insert data into a table from a file. There is a UNIQUE Index that is being violated and the BULK INSERT fails.
I do not want to drop or disable the index, however, i also do not want to load 'duplicate' records so i keep the CHECK_CONSTRAINTS parameter.
Is there a way to have the duplicate records outputed to the ERRORFILE ?
Is there a system table column to query to determine whether an index is defined as unique in SQL Server 2000? It is easy to find this info in SQL Server 2005, but I don't see a valid column for this on dbo.sysindexes.
View 5 Replies View RelatedAll- I have what i'm sure is a question with a simple answer: Supposing I want to modify the select command below to force the display of records with only unique combinations of the two fields person_id and act_session_id (bolded). How would I do this. Note that neither is a key field. (Key field headcount_id was added for completeness.)
Thanks!
SELECT hd.headcount_id, hd.person_id, hd.act_session_idFROM headcount as hd
I am reading "SQL Server Query Performance Tuning Distilled",on page 104 it talks about one of the index design recommendationswhich is to choose the column that has very high selectivity of valuesinstead of a column that has very few selectivity of values.My question is if I have currently indexes on my tables that have1, 2, 3, 4, ... values only on thousands of rows, are these nonclusteredindexes pretty much useless indexes that I should get rid of?And I know that pretty much the number of selectivity values willalways remain very low.Thank you
View 1 Replies View RelatedUma writes "Hi Dear,
I have A Table , Which Primary key consists of 6 columns.
total Number of Columns in the table are 16. Now i Want to Convert my Composite Primary key into simple primary key.there are already 2200 records in the table and no referential integrity (foriegn key ) exist.
may i convert Composite Primary key into simple primary key in thr table like this.
Thanks,
Uma"
Hi all,
Can anyone suggest me on Adding primary key to a table which has already a primary key.
Thanks,
Jeyam
Hi,
I have recently been looking at a database and wondered if anyone can tell me what the advantages are supporting a unique collumn, which can essentially be seen as the primary key, with an identity seed integer primary key.
For example:
id [unique integer auto incremented primary key - not null],
ClientCode [unique index varchar - not null],
name [varchar null],
surname [varchar null]
isn't it just better to use ClientCode as the primary key straight of because when one references the above table, it can be done easier with the ClientCode since you dont have to do a lookup on the ClientCode everytime.
Regards
Mike
We have a table, which has one clustered index and one non clustered index(primary key). I want to drop the existing clustered index and make the primary key as clustered. Is there any easy way to do that. Will Drop_Existing support on this matter?
View 2 Replies View RelatedHi all
I have the following table
CREATE TABLE [dbo].[property_instance] (
[property_instance_id] [int] IDENTITY (1, 1) NOT NULL ,
[application_id] [int] NOT NULL ,
[owner_id] [nvarchar] (100) NOT NULL ,
[property_id] [int] NOT NULL ,
[owner_type_id] [int] NOT NULL ,
[property_value] [ntext] NOT NULL ,
[date_created] [datetime] NOT NULL ,
[date_modified] [datetime] NULL
)
I have created an 'artificial' primary key, property_instance_id. The 'true' primary key is application_id, owner_id, property_id and owner_type_id
In this specific instance
- property_instance_id will never be a foreign key into another table
- queries will generally use application_id, owner_id, property_id and owner_type_id in the WHERE clause when searching for a particular row
- Once inserted, none of the application_id, owner_id, property_id or owner_type_id columns will ever be modified
I generally like to create artificial primary keys whenever the primary key would otherwise consist of more than 2 columns.
What do people think the advantages and disadvantages of each technique are? Do you recommend I go with the existing model, or should I remove the artificial primary key column and just go with a 4 column primary key for this table?
Thanks Matt
Hello all,I'm taking over a project from another developer and i've run into a bit of a problem. This developer had a bad habit of not using primary keys when designing various databases used by his programs. So now i've got approx 1000 tables all of which do not have primary keys assigned. Does anyone know of a tsql script that i can run that will loop through each table and add a primary key field?Thanks in advance?Richard M.
View 2 Replies View RelatedI have a Department Table.
Can any one tell me its Primary Key.
I have the order
AutoNumber, D + AutoNumber, Code,
Can you help me regarding this.
Because some people never like to use AutoNumber.
That's why I am confused.
Hi..
I'm going to build database of university, but I have problem with primaru key,
This is the situation:
there are many faculities and each one has many departments,
each department has many courses,
each course has many sections..
The problem:
I want to make those fields in the same table and make the primary key generate from other fields,
(i.e)
I want the faculity be integer from 4 digit "Example the first faculity start with 1000 the second 2000 and so on" and the the department of each faculity will generate its value from the faculity number+interger number from 3digit "Example the department of the first faculity start with 1100 and the second on will be 1200 and so on "
the same thing will repeate for courses and sections so the sectionsID will be the primary key.
Do you know hoew this idea can be implement by SQL server 2005?
Please help me as soon as possible.
A column will be Primary Key. Others are B and C. I want A will contain B and C. I mean B data is X, C data is Y, A will be XY. How can i do this? Can i set in MSSQL or need ASP.NET?
View 1 Replies View RelatedHeya,
I'm trying to setup a Primary Key on a SQL 6.5 database.
Is there a way to do this? When I hit advanced, it asks for me to select a field for the primary key, but it doesnt list fields to selct from, and I cant type it in.
Thanks for your help,
Hi All,
Using DTS i have imported the data from sybase to MS SQL server and all the data and tables were imported correctly.But the primary keys are not marked why is it like this?
This is not a one time job and this is meant to be for the customers also.I cannot ask the customers to mark the primary keys themselves. Is there a way to get the keys also.While doing DTS I have marked all the options correctly.
Please help.
I am setting up some tables where I used to have an identity column as the primary key. I changed it so the primary key is not a char field length of 20.
Is there going to be a big performance hit for this? I didn't like the identity field because every time I referenced a table I had to do a join to get the name of object.
EG:
-- Old way
tbProductionLabour
ID (pk)| Descr | fkCostCode
----------------------
1 | REBAR | 1J
tbTemplateLabour
fkTemplateID | fkLabourID | Manpower | Hours
--------------------------------------------
1 | 1 | 1 | 0.15
-- New way
tbProductionLabour
Labour | fkCostCode
---------------------
REBAR | 1J
tbTemplateLabour
fkTemplateID | fkLabour | Manpower | Hours
-------------------------------------------
1 | REBAR | 1 | 0.15
This is a very basic example, but you get the idea of what I am referring to.
Any thoughts?
Mike
I need to create my own primary key, how do I go about doing that?? In the database I am working in usually has a primary key that looks like this VL0008
the V is for Vendors, thats basically their number. Some of these Vendors need to be licensed and some dont, the ones that are not licensed dont get a number but I am to use that as the Primary/Index key I need to create one for those particual vendors. How can I go about doing that??? I was wanting to make it TL888 something like that.
i'm having problem to get th primary key from d database....
for your information i'm using java to get the primary key....
this is my code...
rs = stt.executeQuery("sp_columns "+table_db+";");
while(rs.next())
{
out.write(""+rs.getString("COLUMN_NAME"));
out.write(", "+rs.getString("TYPE_NAME"));
out.write(", "+rs.getString("IS_NULLABLE"));
}
rs = stt.executeQuery("sp_foreignkeys @table_name = N'table_db';");
but the problem is....
i get this error message...could anyone tell me what's the problem....
java.sql.SQLException: [Microsoft][ODBC SQL Server Driver][SQL Server]Could not
find server 'table_db' in sysservers. Execute sp_addlinkedserver to add th
e server to sysservers.
how do i solve this problem....
thanx to anyone who can help me...... :D
Please help:
I am creating a table called Bonus:
ProductHeading1
ProductHeading2 (could be null)
ProductHeading3(could be null)
Bonus
Datefrom
DateTo
.... what would be the primary key?! I know it would be DateTo and sumfing...... Since Heading2 and Heading3 could be null, they cannot be PK... and heading1 cannot be a PK because the following three DIFFERENT options could have the same heading1
Option 1) heading1 = "X" heading2 = Null heading3 = Null
Option 2) heading1 = "X" heading2 = "Y" heading3 = Null
Option 3) heading1 = "X" heading2 = "Y" heading3 = "Z"
... but I need a PK to make sure a bonus is not entered twice... I considered added an Id, but them how do I assign a id?! what would i make the id equal to???
Thanks....
Hi all,
Is it possible to have a primary key for SQL or Oracle or jet to have an alpanumeric beginning?
for example
1st District as a primary key
The statement is:
SELECT itemid FROM MASecurity WHERE userid=%d
Thanks,
Jj :)
What 's the way to know
the name of the column that is
the primary key of a table
In a recent course on database programming using Microsoft Access 2002. I noticed that the text entitiled New Perspectives Microsoft Access 2002 stated that a primary key could only be used once per table. But If I am not mistaken could one use the select key to select more than one primary key within a table.
View 8 Replies View RelatedHi guys,
Is there a method in sql server 2005 to format the primary key so it can be alphanumberic?
Thanks.
Violation of PRIMARY KEY constraint 'PK_Dunning_TBL'. Cannot insert duplicate key in object 'Dunning_TBL'.
The statement has been terminated.
(0 row(s) affected)
Msg 2627, Level 14, State 1, Procedure GenerateFiles_FST_SP, Line 220
Violation of PRIMARY KEY constraint 'PK_Exceptions_TBL'. Cannot insert duplicate key in object 'Exceptions_TBL'.
The statement has been terminated.
i got this error how can i resolve this?