Primary Keys: Best Practice: Uniqueidentifier Or?
May 13, 2006I've searched the posts and library. Associates have different ideas on the topic. So what is your opinion?
For SQL 2005, what is the recommended data type for a primary key?
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Auto Incremented Integer Primary Keys Vs Varchar Primary Keys
Aug 13, 2007Hi,
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
Creating Inter-table Relationships Using Primary Keys/Foreign Keys Problem
Apr 11, 2006Hello again,
I'm going through my tables and rewriting them so that I can create relationship-based constraints and create foreign keys among my tables. I didn't have a problem with a few of the tables but I seem to have come across a slightly confusing hiccup.
Here's the query for my Classes table:
Code:
CREATE TABLE Classes
(
class_id
INT
IDENTITY
PRIMARY KEY
NOT NULL,
teacher_id
INT
NOT NULL,
class_title
VARCHAR(50)
NOT NULL,
class_grade
SMALLINT
NOT NULL
DEFAULT 6,
class_tardies
SMALLINT
NOT NULL
DEFAULT 0,
class_absences
SMALLINT
NOT NULL
DEFAULT 0,
CONSTRAINT Teacher_instructs_ClassFKIndex1 FOREIGN KEY (teacher_id)
REFERENCES Users (user_id)
)
This statement runs without problems and I Create the relationship with my Users table just fine, having renamed it to teacher_id. I have a 1:n relationship between users and tables AND an n:m relationship because a user can be a student or a teacher, the difference is one field, user_type, which denotes what type of user a person is. In any case, the relationship that's 1:n from users to classes is that of the teacher instructing the class. The problem exists when I run my query for the intermediary table between the class and the gradebook:
Code:
CREATE TABLE Classes_have_Grades
(
class_id
INT
PRIMARY KEY
NOT NULL,
teacher_id
INT
NOT NULL,
grade_id
INT
NOT NULL,
CONSTRAINT Grades_for_ClassesFKIndex1 FOREIGN KEY (grade_id)
REFERENCES Grades (grade_id),
CONSTRAINT Classes_have_gradesFKIndex2 FOREIGN KEY (class_id, teacher_id)
REFERENCES Classes (class_id, teacher_id)
)
Query Analyzer spits out: Quote: Originally Posted by Query Analyzer There are no primary or candidate keys in the referenced table 'Classes' that match the referencing column list in the foreign key 'Classes_have_gradesFKIndex2'. Now, I know in SQL Server 2000 you can only have one primary key. Does that mean I can have a multi-columned Primary key (which is in fact what I would like) or does that mean that just one field can be a primary key and that a table can have only the one primary key?
In addition, what is a "candidate" key? Will making the other fields "Candidate" keys solve my problem?
Thank you for your assistance.
Creating Indexes On Columns That Are Foreign Keys To Primary Keys Of Other Tables
Jul 16, 2014what the best practice is for creating indexes on columns that are foreign keys to the primary keys of other tables. For example:
[Schools] [Students]
---------------- -----------------
| SchoolId PK|<-. | StudentId PK|
| SchoolName | '--| SchoolId |
---------------- | StudentName |
-----------------
The foreign key above is as:
ALTER TABLE [Students] WITH CHECK ADD CONSTRAINT [FK_Students_Schools]
FOREIGN KEY([SchoolId]) REFERENCES [Schools] ([SchoolId])
What kind of index would ensure best performance for INSERTs/UPDATEs, so that SQL Server can most efficiently check the FK constraints? Would it be simply:
CREATE INDEX IX_Students_SchlId ON Students (SchoolId)
Or
CREATE INDEX IX_Students_SchlId ON Students (SchoolId, StudentId)
In other words, what's best practice for adding an index which best supports a Foreign Key constraint?
Generate Script For Primary Keys And Foreing Keys
May 16, 2008
Pls let me know How I generate script for All primary keys and foreign keys in a table. Thereafter that can be used to add primary keys and foreign keys in another databse with same structure.
Also how I script default and other constraints of a table?
Urgent !!!!! Nee Explanation On Primary Keys And FK Keys
Jul 15, 2002Can somebody explain to me how to best do inserts where you have primary keys and foreign keys.l'm battling.
Is there an article on primary keys/Pk ?
Uniqueidentifier As A Primary Key
Feb 18, 2006Hey can you use the Uniqueidentifier as a primary key or no??
View 4 Replies View RelatedUniqueIdentifier As Primary Key.
Jan 17, 2008SQL2K SP4
Greetings. I just inherited doscovered a 3gb DB that is chewing up lots of CPU time on a pretty beefy server. This DB uses 4 main tables. It has many more, but most of the Inserts/ Updates/ Deletes/ and Joins are done mainly on 4 tables. Anyways, I figured out which sprocs use the most CPU between the hours of 7 and 7 every day, off to a good start. The first one is hardly every run. While it is a pig in terms of CPU usage, the amount of times it's run is somewhat minimal compared to others. So the next one is is a sproc that does auto refreshes, and is run every minute by thousands. I start to analyze it, particularly for missing indexes, but all is well. So I'm beating my head up against the wall and I realize, THE CLUSTERED PRIMARY KEY (PK) FOR THESE TABLES USE A GUID DATA TYPE....
So I have some questions about this data type, and also inserting into a clustered PK in general.
Are joins on this data type as bad as joining on varchar columns in terms of speed?
I don't see that any of my insert sprocs are taking a long time. So if an insert occurs, and a page split needs to happen (which is quite potential with this data type as a clustered PK), does it -- A) Begin the insert, complete the insert, then do a page split? Or does it -- B) Begin the insert, do the page split, then complete the insert?
If A, it would make sense that I would see no lag for my insert sprocs, but also see a high CPU usage (provided I have a high number of page splits, which is yet to be determined. If B, I would expect to see a lot of long running insert sprocs, which I don't.
Using GUID / Uniqueidentifier As Primary Key
Jul 6, 2006<BACKGROUND INFO> We are in the database design stage of creating a db and we plan to use a GUID as the primary key for our tables (the app will be a smart client and will need to support offline functionality so when the app comes back online and the queued up inserts come thru we want to ensure that the primary keys are unique). We plan to have the app generate the guid and to send the GUID over as a parameter i.e.
<code>GUID myPrimaryKey = GUID.NewID(); </code>
and will not be using the DEFAULT NEWID clause on the CREATE TABLE statements.
</BACKGROUND INFO>
<QUESTION > Is it better to make the data type for the primary key columns to be uniqueidentifier or should the datatype be varchar(36).</QUESTION>
I only ask this because the tables have already been created with the primary key columns having a datatype of varchar(36) and changing them would be a little bit of work. Not a big deal but don't want to do it if we don't have to. If its really advantageous we will go ahead and do it but if not we would like to leave it as is. Thanks for your thoughts!
Bo
How To Insert Into A Table With A Uniqueidentifier As Primary Key?
Jun 28, 2006I would like to insert into a table with a primary key that has a uniqueidentifier. I would like it to go up by one each time I execute this insert statement. It would be used as my ReportId
My VB code is this.
Protected Sub btncreate_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btncreate.Click
'set connection string
Dim errstr As String = ""
Dim conn = New SqlConnection("Data Source=.SQLEXPRESS;AttachDbFilename=|DataDirectory|ASPNETDB.MDF;Integrated Security=True;User Instance=True")
'set parameters for SP
Dim cmdcommand = New SqlCommand("sprocInsertNewReport", conn)
cmdcommand.commandtype = CommandType.StoredProcedure
cmdcommand.parameters.add("@UserName", Session("UserName"))
cmdcommand.parameters.add("@Week", vbNull)
cmdcommand.parameters.add("@Date", vbDate)
cmdcommand.parameters.add("@StartTime", vbNull)
cmdcommand.parameters.add("@EndTime", vbNull)
cmdcommand.parameters.add("@HeatTicket", vbNull)
cmdcommand.parameters.add("@Description", vbNull)
cmdcommand.parameters.add("@TakenAs", vbNull)
cmdcommand.parameters.add("@Dinner", vbNull)
cmdcommand.parameters.add("@Hours", vbNull)
cmdcommand.parameters.add("@Rate", vbNull)
cmdcommand.parameters.add("@PayPeriod", vbNull)
cmdcommand.parameters.add("@LastSave", vbNull)
cmdcommand.parameters.add("@Submitted", vbNull)
cmdcommand.parameters.add("@Approved", vbNull)
cmdcommand.parameters.add("@PagerDays", vbNull)
cmdcommand.parameters.add("@ReportEnd", vbNull)
Try
'open connection here
conn.Open()
'Execute stored proc
cmdcommand.ExecuteNonQuery()
Catch ex As Exception
errstr = ""
'An exception occured during processing.
'Print message to log file.
errstr = "Exception: " & ex.Message
Finally
'close the connection immediately
conn.Close()
End Try
If errstr = "" Then
Server.Transfer("TimeSheetEntry.aspx")
End If
My SP looks like this
ALTER PROCEDURE sprocInsertNewReport
@UserName nvarchar(256),
@Week Int,
@Date Datetime,
@StartTime Datetime,
@EndTime DateTime,
@HeatTicket int,
@Description nvarchar(max),
@TakenAs nchar(10),
@Dinner Nchar(10),
@Hours Float,
@Rate Float,
@PayPeriod int,
@LastSave Datetime,
@Submitted Datetime,
@Approved DateTime,
@PagerDays int,
@ReportEnd DateTime
AS
INSERT INTO
ReportDetails
(
rpUserName,
rpWeek,
rpDate,
rpStartTime,
rpEndTime,
rpHeatTicket,
rpTicketDescription,
rpTakenAs,
rpDinnerPremium,
rpHours,
rpRate,
rpPayPeriod,
rpLastSaveDate,
rpSubmittedDate,
rpApprovedDate,
rpPagerDays,
rpReportDueDate
)
VALUES
(
@Username,
@Week,
@Date,
@StartTime,
@EndTime,
@HeatTicket,
@Description,
@TakenAs,
@Dinner,
@Hours,
@Rate,
@PayPeriod,
@LastSave,
@Submitted,
@Approved,
@PagerDays,
@ReportEnd
)
RETURN
Any Ideas?
thx!
Best Practice: Primary Key In Joing Table
Jan 26, 2006hi there,
i have the following joining table (many-to-many relationship)...
CREATE TABLE [dbo].[products_to_products_swatch] (
[products_to_products_swatch_id] [int] IDENTITY (1, 1) NOT FOR REPLICATION NOT NULL ,
[product_id] [int] NOT NULL ,
[products_swatch_id] [int] NOT NULL
) ON [PRIMARY]
GO
question: do i need to include a primary key in this table - being that it is a joing table?
thanks
mike
Should I Create A Non-primary Default Filegroup As A Best Practice?
Nov 7, 2007This is for SQL2k5. The database may be small or big, I don't know (it's going out to multiple customers). I'm wondering if in general it's considered "better" to create a single non-primary default filegroup and put all the objects there, or just leave everything in primary? In one training years back I got the impression that recovering the primary filegroup was important for certain restore operations, so it was always wise to separate them like this.
Thanks for your input,
Mike
MCDBA
Junction/link Table Primary Key: Best Practice Using SQL Server
Nov 30, 2005Hi all,
This is a bit of a general question regarding SQL Server link tables that i hope someone can find the time to answer.
I am looking for the best practice. If I have 3 tables
1) tblCompetition
2) tblTeams
3) tblTeamsInCompetition (this is the link table)
I know the link table should have a related CompetitionID and TeamID,
but should the link table also have a primary key that is an identity
autoincrement by 1 just as you would with the other two tables. In
Access I have never done this, however in SQL Server I have read that
you should do this (but now I can't find the documentation again which
prompts me to ask the question here).
Thanks for taking the time to answer this question.
Primary Keys
Nov 15, 2006"Violation of PRIMARY KEY of restriction 'PK_Approve_Overtime'. The overlapping key cannot be inserted in object 'Dbo.Approve_Overtime'. The statement was ended."
can soemone explain to me why i have this kind of error?
i have this two tables. approve_overtime table has a primary key id_no and application_input table with a primary key of id_no!
all the values from of application_input will be stored also in approve_overtime.
sometimes the datas can be stored.sometimes it cannot and produces an error!
what do u think?
hmmm pls help!
Primary Keys
May 16, 2002Using SQL Svr 7.0. It appears that primary keys are created as nonclustered
unique indexes. Is there a configuration setting I can use to make them be
created as clustered unique indexes?
Primary Keys
Apr 4, 2001If a table has a column defined as Int, Identity(1,1) which is to be used as the primary key, should that index be defined as clustered or non-clustered? In Enterprise manager when you create a PK on a table it defaults to being a clustered index. I am sure the answer depends on the other index requirements and columns in the table but I'd like to see what other ppl think about this.
Thanks!
Two Primary Keys???
Mar 14, 2000I have read that SQL Server tables can't have more than one primary key. I know in Access two keys are allowed. Why can't there be two primary keys in a single table in SQL Server 7.
Thanks
Primary Keys
Jun 15, 2004Hi everyone,
Does someone knows how can I drop a primary key (that I don't know the name) from a table in one sql statement.
Thanks,
Fady
Primary Keys
Feb 19, 2004HI ,
I accidently removed the primary keys from my table by mistake. Is there anyway ,That i can get the PK's back to what is used to be. Need Help pls...... When I try "resetting" the PK I kep getting this error:
'table_name' table
- Unable to create index 'PK_tablename'.
ODBC error: [Microsoft][ODBC SQL Server Driver][SQL Server]CREATE UNIQUE INDEX terminated because a duplicate key was found for index ID 1. Most significant primary key is '1'.
[Microsoft][ODBC SQL Server Driver][SQL Server]Could not create constraint. See previous errors.
[Microsoft][ODBC SQL Server Driver][SQL Server]Warning: The table 'tDetail' has been created but its maximum row size (12521) exceeds the maximum number of bytes per row (8060). INSERT or UPDATE of a row in this table will fail if the resulting row length exceeds 8060 bytes.
[Microsoft][ODBC SQL Server Driver][SQL Server]The statement has been terminated.
Two Primary Keys
May 17, 2004In access you can have two fields that are primary keys with one or the other repeating as long as the combination is not repeated.
i.e.
key1 key2
200410 12345
200410 12346
200410 12588
etc for all 200410 there can not be a repeat of any value of key 2
is there a way to have this dual key in MSSQL :confused:
Primary Keys
Feb 13, 2006Hi
How can 2 columns be clubbed together to form a primary key , i mean I have 2 columns job & Batch , need to club them together to form the primary key
How is it done I mean in the design , how to define that both the columns togethter form a primary key ,
Cause when I go to the table , it allows me to create a PK through the EM only for one column
Please help
Primary Keys
Oct 17, 2007Hi there,
is there any way I can use INSERT so if I try to copy duplicate primary key data, it automatically skips the task and moves on to the next data?
Primary Keys
May 15, 2008I have declared a table with a single column to be a Primary key. If I write 2 records, the first comprsing "A" and the second "a" then I get an exception about violating the uniqueness of the key. Is there a way that I can define the key to be case sensitive.
Many thanks
Help With Primary Keys
May 4, 2007I have two tables with similar primary keys, table a and table b, and I want to find out all the key values that are disimilar between the tables. Can this be done with a select? if so what would it be.
View 5 Replies View RelatedPrimary, Forgein Keys
Dec 29, 2007I am not entirly sure what a forigen key is, is it a unique ID which is the same as the primary key? If adding a foreign key to a table that already has data, will it update each row with a unique ID or will it only create a unique ID on newly inserted records (for the foreign key)? If the foreign key is the same as the primary key then why do we need to even add a foreign key at all?For example a table like: Table Name : Customers--CustomerID uniqueidentity (primary Key)--FirstName nchar Table Name : Orders --OrderID int--CustomerID int Obviuously CustomerID are going to be the same in both tables, so why would you need to add a foreign key on 'CustomerID' to the 'Order' table, can't SQL match the customerID in each table any way? Cheers
View 3 Replies View RelatedRest Primary Keys?
Mar 20, 2008HiI have a database and I been inserting some dummy data into it but now I want to upload it to my website but I want to delete all the dummy data and start the PK back at 1. I truancted all the data but it still keeps counting from the last one.So how do I reset it?
View 6 Replies View RelatedPrimary Keys Question
May 15, 2001Hi,
I have a question on pk?
I have a db which has tables which do not have pk?I want to create Pk on each one of them - infact,I want to alter the table , add one more field and make it the pk .
My question is - do I will have to go to each table,alter it and then create the pk on it or do someone have any script or better way to do it?
Any help is appreciated.
Replication - Primary Keys
May 17, 2001Hi,
Just a continuation to my earlier queries on replication.
I have a db which I want to replicate - it do not have pk?
I do not want to create pk on existing columns - so I thought of creating one more column in all the tables and make them pk .
Any one has any idea if this will work fine or may give any problem which I should be prepare for.
Any thought appreciated -
pvd
Indexes In Primary Keys
May 6, 2005I have a 3rd party app which had a primary key with about 5 fields. The last field of this was a trantype. This app had a posting process which uses this in it's sql. Ran rather slow. We added an individual index to this field and cut processing down 90%. It almost seemded like sl server was ignoring this index. Is this because it was the last field in the primary key index?
View 1 Replies View RelatedBCP And Duplicate Primary Keys
Sep 10, 1998Hi All,
I`m using BCP to import ASCII data text into a table that already has many records. BCP failed because of `Duplicate primary key`.
Now, is there any way using BCP to know precisely which record whose primary key caused that `violation of inserting duplicate key`.
I already used the option -O to output error to a `error.log`, but it doesn`t help much, because that error log contains the same error message mentioned above without telling me exactly which record so that I can pull that `duplicate record` out of my import data file.
TIA and you have a great day.
David Nguyen.
Composite Primary Keys
Jun 25, 2002Newbie question...
I have two tables (categories & listings) which create a many-to-many relationship.
I have created an interim table with the primary keys from each table as a composite primary key...(cat_id & list_id).
How does the interim table get populated with the id's?
When I do an insert statement to insert data into the categories table, the cat_id field is automatically generated...same with the listings table, but when (and how) does the primary key data get into the interim table.
Thanks in advance for the assistance.
Missing Primary Keys
Jun 24, 2004HI Folks ,
I have a problem with the primary keys in my main Db , I want to setup replication and looks like someone tampered with my database by removing the primary keys.and in order to setup replication i need this table to have primary keys .THere are duplicates in that table but they are nessecary...and for this reason the primary keys do not want to "stick" when i try and specify them.Can anybody help
Burner
Forcing Primary Keys
Jun 1, 2006Hi all,
As our DB has no primary keys or indexes ive taken a copy of all populated tables and tried to force primary keys within a new DB.
the problem is all off the tables have multiple datasets within them, a dataset for each year. This causes all instances of ID numbers to not be unique as they are replicated for every year they are active.
Its a school database so a student who has been here for 3 years will have 3 instances of his ID number, one for each years' data set.
So how do i force primary keys if there is no unique identifier? ive been highlighting both data set and ID columns and setting that combination as the primary key.
Essentially i need to analyse the relationships between the tabls in a diagram and also run some speed tests to see how fast the db works when it has indexes and primary keys.
the reason im writing is that ive done this on ten tables and with another 160 to do im just checking im doing the right thing?
greg