Hi,
Can anyone tell what are the specific scenarios where Unique key is recommened over primary key ?
While designing a database table in what all cases we should think about going for Unique key rather than a primary key.
Regards,
Amit
Hello
for MS SQL 2000 I want to CREATE a Table as follow :
CREATE TABLE [dbo].[Local] (
[id_Local] [int] IDENTITY(1,1) NOT NULL,
[Name] [nvarchar] (100) NOT NULL,
[Info] [nvarchar] (100) NULL
)
id_Local is PrimaryKey autoincrement
but Name must be UNIQUE (not 2 times the same name)
how can script it ?
thank you
hello all sorry m asking Database Question .. m talking about SQL SERVER 2005 but i have bit confusion... what difference between a
primary key and a unique key? if m not wrong then primary key doesn't allow NULLs, but
unique key allows NULLs but in many searches comes that primary key doesn't allow NULLs, but
unique key allows one NULL only. what this means 'one NULL only'?? according to my practical we can give more then 1 nulls... plz clear this point???
Is there any way to auto generate the unique primary key when inserting data in MS SQL?
there is a way to create the increasing integer as primary key, but is there any ways other than that?
thank you
For our database application we get our primary keys by calling a stored procedure that pass's in the table name and outputs the next primary key number assigned to that table.
ALTER procedure [dbo].[sp_getNextKey]
@TableName char(100),
@NextKey T_ID output
as
SET TRANSACTION ISOLATION LEVEL READ COMMITTED
begin transaction
select @NextKey = NextKeyValue from T_KeyGenerator where TableName like @TableName
update T_KeyGenerator set NextKeyValue = NextKeyValue + 1 where TableName like @TableName
commit transaction
I then take that primary key, and other data, and insert that into the desired table.
The Problem I am having is that my user's keep getting "cannot insert duplicate key in table".
So I assume that I do not have the transaction set right, or missing something.
I need it to lock the row in the t_keyGenerator table so that no other users can view that row until I update it with the new value and commit the transaction.
Any help would be greatly appreciated
I wrote this stored procedure and it works fine, it seems. The questions I have are as follows:
(1) What is the difference between PRIMARY KEY and UNIQUE. They seem to pertain to the same behavior. When I used only UNIQUE as qualifier I did not see that the column was marked as primary in the SQL Management Studio.
What I need is for a column to be unique in the sense that it would not allow duplicate values and it must have an INDEX on it. I need it to be descending.
(2) Did I do it right or there are aspects in here I do not quite see?
set ANSI_NULLS ON
set QUOTED_IDENTIFIER OFF
GO
ALTER PROCEDURE [dbo].[CreateTableDailyClose]
@symbol varchar (10) = null
AS
BEGIN
SET NOCOUNT ON;
DECLARE @SQL VARCHAR(500)
SET @SQL = 'CREATE TABLE dbo.dailyCl_' + @symbol + ' (
dateTimed DateTime NOT NULL PRIMARY KEY,
opened float NULL,
high float NULL,
low float NULL,
closed float NULL,
volume int NULL,
adjClosed float NULL
)'
EXEC sp_sqlexec @Sql
SET @SQL = 'CREATE UNIQUE INDEX dateTimed ON dbo.dailyCl_' +
@symbol + ' (dateTimed DESC) '
EXEC sp_sqlexec @Sql
END
Thanks.
my table :
CREATE TABLE [dbo].[users] (
[ID] [int] NOT NULL ,
[A1] [nvarchar] (100) NULL ,
[A2] [nvarchar] (100) NULL ,
[A3] [nvarchar] (100) NULL
) ON [PRIMARY]
i must keep ID columns as primary key
ALTER TABLE [dbo].[users] WITH NOCHECK ADD
CONSTRAINT [PK_users] PRIMARY KEY CLUSTERED
(
[ID]
) ON [PRIMARY]
but now A1+A2 must be unique
how can i do it ?
thank you
Question: I have a test table like this
CREATE TABLE [dbo].[Test](
[name] [varchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL,
[addr] [varchar](50) COLLATE SQL_Latin1_General_CP1_CI_AS NULL,
CONSTRAINT [PK_Test] PRIMARY KEY CLUSTERED
(
[name] ASC
)WITH (PAD_INDEX = OFF, IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
But when I tried to input my data like
'abc', '123 abc'
'abc ','123 abc'
SQL server won't recognize 'abc' and 'abc ' is a different value if the last character is a space. Is there a way to make it as a different value? I tried to drop the primary and input the data. When I ran a group by the name column, 'abc' show 2 instead of 1. Seems SQL server is trying to ignore the space at the end too.
I also noticed unique index have the same problem too. Please help.
What is the need of Primary Key if everything can be achieved by Unique Key? Everything that primary key does, Unique key can also fill those things.Why primary key is required?
View 4 Replies View RelatedHi,
I am making a program in Visual Basic .NET with SQL Server 2000.
I have a table "MyTable" with a primary key named "Id". The primary key is 'Create Unique' checked and 'Index' selected. When I insert all the fields required, except "Id" of course, I need the new record's "Id" in my VisualBasic program, but I don't know how...
I must do one of them, but don't know how either of them:
-Create a trigger on insertion that will send to the user that sended the insert command the "Id" of the record just created.
or
-get the command in Visual Basic that will send the Insert command with a return field ("Id")
Thanks in advance,
Sebastien Anselmo
I have a deal table, each of these investments must be unique. I created a int pk : idDeal. Does that make sense or should i just use the deal colm being it has a unique constraint,
Reguarding indexes, should i make the auto # colm my pk and make that the clustered index? and put another index on the Deal Colmn? Any suggestions welcomed
Thank you
Hi
I have a strange requirement in ETL operation. My Source contains only the details table data. Out of it, I have to load the master table and refer the Master table primary key ID to load Details table. I can easily load the Master Table with aggregate transformation. But problem is how to look up the Master Table Primary Key ID to load the Details table, as the master does not contains any unique key to lookup. This may seems to be strange but this is my requirement. You can refer the Source and Destination data model as below. They may give you clear picture. Can you guys help me out on this?
My Source Table
--------------------------
Citye Type
City Name
Source
New York
Via City1
Pittsburg
Destination City
Chicago
Source
New York
Via City1
Philadelphia
Destination City
Chicago
My Destination
------------------------
Master Table
ID
1
2
Detail Table
Master Table ID
Citye Type
City Name
1
Source
New York
1
Via City1
Pittsburg
1
Destination City
Chicago
2
Source
New York
2
Via City1
Philadelphia
2
Destination City
Chicago
Thanks
Hi,
Te following situtation is :
ReportModel is created ,there is only a named query in DSV ,it has a few tables in it(The relationship are inner joins and outer joins).
The question is how could I create a unique logical primary key to identify each unique row in the named query dataset, and also you cannt generate a model unless the named query has a logical primary key . how can I solve this problem,any help?
We are going to use SQL Sever change tracking. The problem is that some of our tables, which are to be tracked, have no primary keys. There are only unique clustered indexes. The question is what is the best way to turn on change tracking for these tables in our circumstances.
View 4 Replies View RelatedHello,
I have a table which has a composite primary key consisting of four columns, one of them being a datetime called Day.
The nice thing afaik with this composite key is that it prevents duplicate entries in the table for any given day. But the problem is probably two-fold
1. multiple columns need to be used for joins and I think this might degrade performance?
2. in client applications such as asp.net these primary keys must be sent in the query string and the query string becomes long and a little bit unmanagable.
A possible solutions I'm thinking of is dropping the existing primary key and creating a new identity column and a composite unique index on the columns from the existing composite key.
I would like to have some tips, recommendations and alternatives for what I should do in this case.
I have following script which i am planning to run to drop all non-clustered primary keys on a database and then created as clustered. I am using someone else's script so don't know how to modify this. Some of primary key columns are used in references in other tables.
is there anyway i can drop the existing primary keys and using their original script then create again as clustered including restoring all foreign and reference keys and unique or no unique.
DECLARE @table NVARCHAR(512), @tablename NVARCHAR(512),
@sql NVARCHAR(MAX), @sql2 NVARCHAR(MAX), @sql3 NVARCHAR(MAX),
@column NVARCHAR(MAX);
DECLARE @indexname NVARCHAR(512);
SELECT name As 'Table'
[Code] ....
This index is not unique
ix_report_history_creative_id
Msg 2601, Level 14, State 1, Procedure DFP_report_load, Line 161
Cannot insert duplicate key row in object 'dbo.DFP_Reports_History' with unique index 'ix_report_history_creative_id'.
The duplicate key value is (40736326382, 1, 2015-07-03, 67618862, 355324).
Msg 3621, Level 0, State 0, Procedure DFP_report_load, Line 161
The statement has been terminated.
Exception in Task: Cannot insert duplicate key row in object 'dbo.DFP_Reports_History' with unique index 'ix_report_history_creative_id'. The duplicate key value is (40736326382, 1, 2015-07-03, 67618862, 355324).
The statement has been terminated.
A UNIQUE INDEX must inherently impose a unique constraint and a UNIQUE CONSTRAINT is most likely implemented via a UNIQUE INDEX. So what is the difference? When you create in Enterprise Manager you must select one or the other.
View 8 Replies View RelatedHelloWhat should I use for better perfomance sinceunique constraint always use index ?ThanksKamil
View 5 Replies View RelatedWhat's the difference in the effect of the followings:
CREATE UNIQUE NONCLUSTERED INDEX
and
ALTER TABLE dbo.titles ADD CONSTRAINT
titleind UNIQUE NONCLUSTERED
I found there're two settings in Indexs/Keys dialog box of the management studio, Is Unique, and Type. The DDL statements above are generated by setting Is Unique to yes plus Type to Index, and just Type to Unique Key, respectively. What's the difference between them?
Hi everyone,
I need urgent help to resolve this issue...
As far as the performance goes which one is better..
Unique Index(col1, col2) OR Unique constraint(col1, col2) ?
Unique constraint automatically adds a unique index
and unique index takes care of uniqueness then whats the use of unique constraint ?
Which one do one use ?
thanks
sonali
BOL says a unique constraint is preferred over a unique index. It also states that a unique constraint creates a unique index. What then is the difference between the two, and why is a constraint preferred over the index?
View 2 Replies View Related
hi team,
.Can i create umique constraint with out unique index.when i am creating a unique constraint sql creates a unique index (default) can i have only unique constraint ?
I am having a problem trying to figure out the best way to get the results I need. I have a table of part numbers that is joined with a table of notes. The table of notes is specific to the part number and user. A row in the notes table is only created if the user has entered notes on that part number. I need to create a search that grabs all matches on a keyword and returns the records. The problem is that it currently returns a row from the parts table with no notes and a separate row with the notes included if they had created an entry. It seems like this should be easy but it eludes me today.
Here is the code
Code Snippet
create procedure SearchPartKeyword
(
@Keyword varchar(250) = null,
@Universal_Id varchar(10) = null
)
as
select p.PartNumber, p.Description, p.ServiceOrderable, n.MyNotes, p.LargestAssembly, p.DMM,
p.Legacy, p.Folder, p.Printer
from Parts p inner join notes n on p.PartNumber = n.Identifier
where n.Universal_ID = @Universal_ID and p.Description like @Keyword
union
select p.PartNumber, p.Description, p.ServiceOrderable, '' as MyNotes, p.LargestAssembly,
p.DMM, p.Legacy, p.Folder, p.Printer
from Parts p
where p.Description like @Keyword
and the results:
PartNo Description SO Notes LA DMM Legacy Folder Printer
de90008 MAIN BOARD 1 DGF1 114688 0 0 0
de90008 MAIN BOARD 1 I love this part Really I do DGF1 114688 0 0 0
This could return multiple part numbers and If they have entered notes I want the row with the notes
Thank You
Dominic Mancl
What 's difference between Unique key and unique index in SQL server 2005?
View 9 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
Here is the table I created:
create table Test (
[recId] [int] identity(1, 1) not null,
[code] [varchar](50) not null,
[prime] [bit] not null constraint [DF_Test_prime] default (cast(0 as bit)),
constraint [PK_Test] primary key clustered
(
[recId]
) with fillfactor = 90 on [primary]
) on [primary]
go
insert into Test (code, prime) values ('AVA', cast(1 as bit))
insert into Test (code, prime) values ('BUS', cast(1 as bit))
insert into Test (code, prime) values ('BUS', cast(0 as bit))
insert into Test (code, prime) values ('BUS', cast(0 as bit))
insert into Test (code, prime) values ('CAR', cast(1 as bit))
insert into Test (code, prime) values ('CAR', cast(0 as bit))
insert into Test (code, prime) values ('RLW', cast(1 as bit))
insert into Test (code, prime) values ('RLW', cast(0 as bit))
insert into Test (code, prime) values ('RLW', cast(0 as bit))
select *
from Test
I need to create a constraint on this table that will not allow me to have two rows that are prime for the same code. So the following insert statement should fail:
-- This should fail
insert into Test (code, prime) values ('RLW', cast(1 as bit))
Thanks for you help!
Regards,
Anand
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
in sql server 2000
i know how to make primary key using enterprise manager
i want to make one of the columns foreign key,how to do that using enterprise manager.and what is the difference between both.
I have one table called agents.
In this table there are two columns, one called "company number" (NUMBER) and one called "company name" (VARCHAR). I have an index called agents_PK that are unique and indexes both columns with company number as first and company name as second in the column order.
But when I look at the data in the column company number its not unique, I find several rows with the same number.
How come ?
Regards Mattias