Surrogate Or Composite Key?
Aug 21, 2004
The orininal design of my db (part of it...) is the following
A JOB has a Number and a Description.
Each JOB can have one or two TASKS (min one, max two). Each TASK is identified by the JOB it belongs to and an Index (unique only for the same JOB).
Each TASK has one an only one set of INFO1, one and only one set of INFO2, one and only one set of INFO3 etc.
A: JOB (JobNum [PK], JobDescription, ...)
B: TASK (JobNum [PK] [FKa], Index [PK], TaskDescription, ...)
C: INFO1 (JobNum [PK] [FKb], Index [PK] [FKb], ...)
D: INFO2 (JobNum [PK] [FKb], Index [PK] [FKb], ...)
(There is a reason to keep INFO1, 2 and 3 separate, because eachof them will be linked to different table. This might influence the answer to my real question.)
First of all, I wouldn't add any surrogate key for TASK, not to loose the logic behind; plus I'd put an ined on JonMum only, being Index equal to 1 or 2 only, so not selective.
The real question is about INFO1 (and 2, 3 etc.) table: should I leave JobNum and Index as PK (consider that the PK of INFo1 will be used as FK for another table), or should I use a surrogate key, like for eaxmple
C: INFO1 (Info1ID [PK], JobNum [FKb], Index [FKb], ...)
I don't really like this solution. Actually I'd prefer the following
C: INFO1 (Info1ID [PK], ...)
where Info1ID = JobNum + Index (+ = string concatenation).
Any suggestion?
Thanks
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Aug 23, 2004
My previous post was not really clear, so I'll try again with a (hopefully) better (even if longer) example...
Consider the following...
A JOB describes the processment of a document.
Each document can exist in two versions: English and French.
A JOB can have 1 or 2 TASK, each describing the processement of either the English or French version.
So we have the following:
A: JOB (JobNum [PK], DocReference, StartDate, EndDate, ...)
B: TASK (JobNum [PK] [FKa], Version [PK], Priority, ...)
that is there is an identifying 1:M (where maxium allowed for M is 2) relationship between JOB and TASK; TASK being identified by JobNum and Version (where the domain for Version is {E, F}).
Each TASK may require a TRANSLATION sub_task.
Each TASK may require a TYPING sub_task.
Each TASK may require a DISTRIBUTION sub_task.
For example, for a given doc, the English TASK requires TRANSLATION and DISTRIBUTION, while the French only DISTRIBUTION.
That is, there is a 1:1 not-required relationship between TASK and TRANSLATION, TYPING and DISTRIBUTION.
So we have the following:
A: JOB (JobNum [PK], DocReference, StartDate, EndDate, ...)
B: TASK (JobNum [PK] [FKa], Version [PK], Priority, ...)
C: TRANSLATION (JobNum [PK] [FKb], Version [PK] [FKb], DueDate, ...)
D: TYPING (JobNum [PK] [FKb], Version [PK] [FKb], DueDate, ...)
E: DISTRIBUTION (JobNum [PK] [FKb], Version [PK] [FKb], Copies, ...)
As you can see I am using the PK of TASK as FK and PK for each of the three SUB_TASKs.
To complicate things, each SUB_TASK has one or more assignments. The assignments for each SUB_TASK records different information from the others.
So we have...
A: JOB (JobNum [PK], DocReference, StartDate, EndDate, ...)
B: TASK (JobNum [PK] [FKa], Version [PK], Priority, ...)
C: TRANSLATION (JobNum [PK] [FKb], Version [PK] [FKb], DueDate, ...)
D: TYPING (JobNum [PK] [FKb], Version [PK] [FKb], DueDate, ...)
E: DISTRIBUTION (JobNum [PK] [FKb], Version [PK] [FKb], Copies, ...)
F: TRA_ASSIGN (JobNum [PK] [FKc], Version [PK] [FKc], Index [PK], Translator, ...)
G: TYP_ASSIGN (JobNum [PK] [FKd], Version [PK] [FKd], Index [PK], Typyst, ...)
H: REP_ASSIGN (JobNum [PK] [FKe], Version [PK] [FKe], Index [PK], Pages, ...)
that is there is an identifying 1:M relationship between each SUB_TASK and its ASSIGNMENTs, each ASSIGNMENT being identified by the SUB_TASK it belongs to and an Index.
I wish I could send a pic of the ER diagram...
Maybe there is another and better way to model this: if so, any suggestion?
Given this model, should I use for TRANSLATION, TYPING and DISTRIBUTION a surrogate key, instead of using the composite key, like for example:
C: TRANSLATION (TranslationID [PK], JobNum [FKb], Version [FKb], DueDate, ...)
D: TYPING (TypingID [PK], JobNum [FKb], Version [FKb], DueDate, ...)
E: DISTRIBUTION (DistributionID [PK], JobNum [FKb], Version [FKb], Copies, ...)
this will "improve" the ASSIGNMENTs tables:
F: TRA_ASSIGN (TranslationID [PK] [FKc], Index [PK], Translator, ...)
G: TYP_ASSIGN (TypingID [PK] [FKd], Index [PK], Typyst, ...)
H: REP_ASSIGN (DistributionID [PK] [FKe], Index [PK], Pages, ...)
I could even go further using a surrogate key even for TASK, which leads me to the following:
A: JOB (JobNum [PK], DocReference, StartDate, EndDate, ...)
B: TASK (TaskID [PK], JobNum [FKa], Version , Priority, ...)
C: TRANSLATION (TaskID [PK] [FKb], DueDate, ...)
D: TYPING (TaskID [PK] [FKb], DueDate, ...)
E: DISTRIBUTION (TaskID [PK] [FKb], Copies, ...)
F: TRA_ASSIGN (TaskID [PK] [FKc], Index [PK], Translator, ...)
G: TYP_ASSIGN (TaskID [PK] [FKd], Index [PK], Typyst, ...)
H: REP_ASSIGN (TaskID [PK] [FKe], Index [PK], Pages, ...)
I don't really like this second solution, but I'm still not sure about the first solution, the one with the surrogate key only in the SUB_TASks tables.
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Jun 21, 2015
So, I have some questions about best practice in SQL Server.
1.) I have PK like this (company TINYINT, store TINYINT, action TINYINT, invoice INT, sn SMALLINT). I know JOINS will work faster with surrogate key but I have only couple of JOINS on that table. I use members of PK in WHERE clause mainly, alone and combined for reporting purpose. Is it always better to have surrogate key because they don't have any meaning and context of data laying in current PK.
2.) In my PK from above I have two candidates for using Sequence object. Invoice start with 1 for every (company,store,action) combination. Sn start with 1 for every (company,store,action,invoice) combination. I would like to know can I implement Sequence object here knowing that Sequence don't support PARTITION BY in OVER clause. From what I red it cannot be done via Sequence but I have to ask.Here is data sample for this PK
company store action invoice sn
----------- ----------- ----------- ----------- -----------
1 1 1 2017 1
1 1 1 2018 1
1 1 1 2019 1
1 1 1 2019 2
1 1 1 2019 3
1 1 2 1 1
1 1 2 2 1
1 1 2 2 2
1 1 2 2 3
1 1 2 3 1
1 1 2 3 2
1 1 2 3 3
1 1 2 3 4
1 1 2 3 5
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Feb 20, 2007
Hello,
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.
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Nov 3, 1999
hi!
when i read some reference books about the SQL7.0, i often met 'surrogate key'. what's the surrogate key? what's its funtion? could you give me a good example?
thanks very much!
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Sep 19, 2006
Hi gurus
can any one tell me what is the best way to use surrogate key (except uniqueidentifier datatype)? how can I use with TSQL?
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Dec 5, 2007
Hi,
How to create surrogate key in a dimension table?
What transformations can be used to create it?
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Jan 16, 2006
Hi, I'm trying to use the SK script from Donald Farmers book but the code isn't accepted
Imports System
Imports System.Data
Imports System.Math
Imports Microsoft.SqlServer.Dts.Pipeline.Wrapper
Imports Microsoft.SqlServer.Dts.Runtime.Wrapper
Public Class ScriptMain
Inherits UserComponent
Dim CurrentKey As Integer
Public Overrides Sub PreExecute()
CurrentKey = CInt(Me.Variables.FILCodesSK)
End Sub
Public Overrides Sub Input_ProcessInputRow(ByVal Row As Input0Buffer)
CurrentKey += 1
Row.SurrogateKey = CurrentKey
End Sub
End Class
There is a problem with the use of the overrides on the Input_ProcessInputRow sub should this be renamed?
Cheers, Al
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Jun 10, 2008
Hey All, I'm trying to decide what's the 'best' to use. I've been designing and creating database for a while and have pretty much always used a surrogate key and not a normal one. I've finally had some free time to start studying more so in my spare time and read up and come accross a lot of guides, articles and stories that tout that normal keys should be used whenever possible as they're a better identifier and that surrogate keys should only be used when there is not a readily available normal key. Now perhaps I'd be open to accepting that but absolutely every database I come across tends to only use surrogate keys. For example I'm doing an authentication system from scratch and am looking at the User table. Now of course the user name has to be unique, should that be the primary key or should I have a seperate column with a guid or an incrementing int or the like as the primary key? I can certainly see that username could be used. I can also see how it may be easier when looking through the data tables to identify who/what a table is refering to with a surrogate key. However it still seems sort of sloppy, for lack of a better word, to me. Where now I could have somebody's username (or any other piece of data used for this purpose) spread accross a lot of other tables. And while writting this I just thought of the scenario that perhaps somebody needs their username changed, with this method now the ids need to be changed on all the related rows of all the other tables whereas with a surrogate key it wouldn't matter. Anyways I'm mostly looking for opinions on which way to go (not just with the user sample, but more in general).Thanks.
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Jan 22, 2001
Hello
I'm looking for a way of generating the next key value that works in MS and Sybase SQL Servers. Sybase identity columns are a bit dodgy, so...
If I have a separate table NextKey (NextKey int) with one row that I update as follows...
declare @NextKey int
update NextKey set NextKey = NextKey + 1, @NextKey = NextKey + 1
insert into myTable (PrimaryKeyCol, ....) values (@NextKey, ....)
are there any problems with concurrency ? As I see it the update will lock the row so different connections will always come up with a different @NextKey value....
Thanks
John
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May 19, 2008
I am performing a Select Into from a #table into a real table that has a surrogate key. If this is in a transaction (or not in one) am I guaranteed that the records inserted will be sequential surrogate key ids?
Select * into REALTABLE from MYPOUNDTABLE --40 rows
Can I assume that if the first one inserted is id 32 that the last one is 72?
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Jul 20, 2005
{CREATE TABLEs and INSERTs follow...}Gents,I have a main table that is in ONE-MANY with many other tables. For example, ifthe main table is named A, there are these realtionships:A-->BA-->CA-->DA-->EWith one field in Common (Person). The tables B, C, D and E are History tables,with Start and End dates. Each person has a Program history (table B, ie), anExperience history (table C, ie), and so on...many differernt types ofhistories, and it may grow from here....table F, G, etc.The included CREATE TABLEs and INSERTs contain tables A, B and C.The problem: Each tblCase (table A) record has a date. When joining all of thehistory tables to tblCase on Person, obviously you get a cross-product of eachhistory unless you specify a WHERE clause that extracts one single record fromeach of the histories (duh...that's the point...to extract a single record fromeach history, because there can only be one value in effect at the time of theCase.)QUESTION: From a performance standpoint, would it behoove me to maintain thesurrogate ***HistoryID from each history table in tblCase, or, assuming theindexes are set up properly, would a WHERE condition for each history besufficient? For example, the following select works as expected:SELECT CasePerson, CaseDate, ProCode, ExpYearFROM tblExperienceHistory INNER JOIN (tblCase INNER JOIN tblProgramHistory ONtblCase.CasePerson = tblProgramHistory.ProPerson) ON tblCase.CasePerson =tblExperienceHistory.ExpPersonWHERE CaseDate BETWEEN ProStartDate and ProEndDateAND CaseDate BETWEEN ExpStartDate and ExpEndDateIt extracts the single record from each history for each person for each case.But I'm afraid of performace with such a scenario.Instead, I could store each ***HistoryID in the table tblCase, and then justjoin on that...no WHERE needed. But the trade-off is that I'd have to buildprocesses to maintain that. ("Hey, when you insert a record into tblCase, makesure to go get each HistoryID from the History tables!" or "If the user changesthe date ranges in one of histories, make sure to update tblCase to match thenew historyID!")Maybe a clustered index on each ***History table on Person/StartDate combinedwith the WHERE clause should perform as well as a real JOIN on surrogateintegers.It seems cheesey to have to resort to surrogate IDs...but the performanceincrease might be worth it. Also, if I go that route, whenever I add a newhistory table, I'd have to change the design of tblCase AND any SPs thatreference it. With the WHERE solution, I'd only have to change the SPs.Comments are welcome! (tblCase grows at 250,000 records per year; the historytables will increase about 1000 records per year)DCMFANCREATE TABLE [dbo].[tblCase] ([CaseID] [char] (5) CONSTRAINT [PK_tblCase] PRIMARY KEY CLUSTERED NOT NULL ,[CaseDate] [smalldatetime] NOT NULL ,[CasePerson] [char] (5) NOT NULL) ON [PRIMARY]GOCREATE TABLE [dbo].[tblExperienceHistory] ([ExperienceHistID] [int] IDENTITY (1, 1) NOT NULL ,[ExpPerson] [char] (5) NOT NULL ,[ExpStartDate] [smalldatetime] NOT NULL ,[ExpEndDate] [smalldatetime] NOT NULL ,[ExpYear] [int] NOT NULL) ON [PRIMARY]GOCREATE TABLE [dbo].[tblProgramHistory] ([ProgramHistID] [int] IDENTITY (1, 1) NOT NULL ,[ProPerson] [char] (5) NOT NULL ,[ProStartDate] [smalldatetime] NOT NULL ,[ProEndDate] [smalldatetime] NOT NULL ,[ProCode] [int] NOT NULL) ON [PRIMARY]GOINSERT INTO [tblCase]([CaseID], [CaseDate], [CasePerson])VALUES('12345', '3/1/03', '00000')INSERT INTO [tblCase]([CaseID], [CaseDate], [CasePerson])VALUES('A1G34', '4/23/03', '00001')INSERT INTO [tblExperienceHistory]([ExpPerson], [ExpStartDate], [ExpEndDate],[ExpYear])VALUES('00000', '1/1/03', '5/19/03', 1)INSERT INTO [tblExperienceHistory]([ExpPerson], [ExpStartDate], [ExpEndDate],[ExpYear])VALUES('00000', '5/20/03', '12/31/03', 2)INSERT INTO [tblExperienceHistory]([ExpPerson], [ExpStartDate], [ExpEndDate],[ExpYear])VALUES('00001', '4/20/03', '11/1/03', 0)INSERT INTO [tblProgramHistory]([ProPerson], [ProStartDate], [ProEndDate],[ProCode])VALUES( '00000', '2/1/03', '9/30/03', '55555')INSERT INTO [tblProgramHistory]([ProPerson], [ProStartDate], [ProEndDate],[ProCode])VALUES( '00000', '10/1/03', '5/1/04', '55555')INSERT INTO [tblProgramHistory]([ProPerson], [ProStartDate], [ProEndDate],[ProCode])VALUES( '00001', '1/1/03', '12/31/03', '55555')
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May 19, 2008
I am performing a Select Into from a #table into a real table that has a surrogate key. If this is in a transaction (or not in one) am I guaranteed that the records inserted will be sequential surrogate key ids?
Select * into REALTABLE from MYPOUNDTABLE --40 rows
Can I assume that if the first one inserted is id 32 that the last one is 72?
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Jan 23, 2008
I have two tables:
countries(country_id integer, country_name string)
authors(auth_id integer, country_id integer, auth_name string)
...Where "country_id" in the authors table refers to the same country_id in the countries table.
I want a stored procedure to handle the insertion of new rows in the authors table. There are two methods of doing it:
1) CREATE PROCEDURE addAuthor( authorName, countryId )
And
2) CREATE PROCEDURE addAuthor( authorName, countryName )
Now, I like #1 because the implementation is simple -- the calling code simply passes an author name, and a country id and an INSERT INTO statement is called with those parameters
INSERT INTO authors( @authorName, @countryId )
I like #1, because it hides the surrogate "id" key from the application calling code. But on the downside, it has more overhead work, because you have to first a) verify a country with that name exists, and b) select that id into a variable.
DECLARE id INT;
IF EXISTS (select * from countries where country_id = @countryId ) THEN
SELECT country_id INTO id FROM countries WHERE country_name = @countryName;
END IF;
(Sorry I may have the SQL syntax wrong up there, but I was just trying to demonstrate the extra overhead involved).
Which approach do you guys think is better?
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May 21, 2008
I am in the process of building a fact table in a staging area. The data in the host system has numerous composite keys, so I have replaced all the composite keys in the dimensions with surrogate keys (integer) which are generated using an identity at load time. When I load the staging (fact) table, I have set the default value of all the foreign keys to 0. What I must do now is update all the foreign key values with the surrogate key values from the dimensions. I'm using an update command and the original gid values from the source system in the where clause...i.e.
UPDATE X
SET x.key_1 = y.key_1
FROM TableA X WITH (NOLOCK)
INNER JOIN TableB Y WITH (NOLOCK)
ON x.org_id = y.org_id
AND x.bus_id = y.bus_id
AND x.prov_gid = y.prov_gid
AND x.log_gid = y.loc_gid;
This seems to work fine for most tables. However, I am now trying to update a table that has over 10 million rows and approximately 30 foreign keys. The script runs for hours. I ususally stop it after about 8 hours when it still hasn't completed. Since the keys are dynamic and they could possibly change during each load process, I can't add them during the load process.
Is there a better way to update these keys. I need to regenerate the fact tables every night and taking this much time to reload a fact table is just not practicle. I've indexed the alternate keys on all the dimensions and have also indexed the gids on the target fact table. Am I doing something wrong? Have I over indexed the target table? Please help! Thanks Jerry
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Jul 22, 2007
Hi,
I have a dimension called 'Caller Type' with the following attributes:
CallerTypeKey ---- surrogate key
CallerTypeID
CallerTypeDesc
CreatedByKey ---- foreign surrogate key from User Dimension
I used Script Task to get the last used key and increment it so i can use it for new records in my dimension. however, my dimension is linked to a User Dimension and I need the surrogate key of that once I insert the new record to CallerType Dimension.
How would I do that?
cherriesh
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May 2, 2006
This is the code iam using to get the incremental surrogate keys:
Imports System
Imports System.Data
Imports System.Math
Imports Microsoft.SqlServer.Dts.Pipeline.Wrapper
Imports Microsoft.SqlServer.Dts.Runtime.Wrapper
Public Class ScriptMain
Inherits UserComponent
'Declare a variable scoped to class ScriptMain
Dim counter As Integer
Public Sub New() 'This method gets called only once per execution
'Initialise the variable
counter = 1093
End Sub
'This method gets called for each row in the InputBuffer
Public Overrides Sub Input_ProcessInputRow(ByVal Row As InputBuffer)
'Increment the variable
counter += 1
'Output the value of the variable
Row.instance = counter
End Sub
End Class
--'Instance' is my surrogate feild name
but iam getting an error saying that InputBuffer is not defined ..Any idea?
If I want to add two more incrementive fileds ,where i have to add it?
Sorry if it sounds silly ,iam very new to this scripting.
Thanks
Niru
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Jul 18, 2006
I have a database surrogate key that increments so rapidly (+5000 every 30 mins). I need my SSIS package to reset this database surrogate key to avoid reaching an upper limit value for that field.
How can I do that using SSIS package?
thanks,
Aref
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Jun 12, 2007
I have several stage to star (i.e. moving data from a staging table through the key lookups into a fact table) ETL transformations in a single SSIS package. Each fact table has a different set of measures but the identical foreign key set, e.g. ConsultantKey, SubsidiaryKey, ContestKey, ContestParamKey and MonthKey.
Currently I have to replicate the key lookup (Surrogate Key Pipeline, or SKP) for each data flow. If I could cache each dimension one time in the package and reuse it for each stage to fact it would be much more efficient.
Is there a way for me to reuse a common data flow?
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Oct 2, 2006
I am trying to write a ssis surrogate key data transform, my problem is I can't find an example how to add a column to the incoming columns and add some data to it. If anyone has a sample, can you please post it. I found a script option that works but I would like an actual transform.
Thanks
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Jun 3, 2015
I want to change the work table name to work_version2 and later drop the work table. First, I created the table (work_version2) along with the data structure seen below and later inserted data from the work table. As I tried to make workID a surrogate key in work_version2 using SSMS, I got the below error message when I try to save the changes. Is there a way to do this?
Saving changes is not permitted. The changes you have make requires the following tables to be dropped and re-created. You have either make changes to a table that cant't be recreated or enabled the option that prevent saving changes that requires the table to be recreated. Work_version2.
CREATE
TABLE WORK(
WorkID Int NOT
NULL IDENTITY (500,1),
Title Char(35) NOT
NULL,
Copy Char(12) NOT
[Code] ....
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Jul 19, 2007
Hi,
I have tables like the one below for my Stage and dimension tables:
Stage Table
accountid
name
address
Dimension Table
accountkey ---- surrogate key (DW key)
accountid ---- business key (transaction's primary key)
name
address
I used slowly changing dimension to detect the changes for the records inside my Dimension table. But I had a problem when a new record exists in the stage table. The accountkey is set as the primary key and it gets its value from a different table which stores the last account key that was created. I cannot load all the changes unless i have a business key. Is there a way that i can get the "last key" from a different table in the data flow area and then supply it together with the other fields in the new output branch of the slowly changing dimension?
cherriesh
thanks!
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Apr 30, 2015
I want to create an import table for daily rows with an integer column like 20150430 for the date, called DayKey. This table would do one date per day. It would then be imported into a STAGE table which would have the same columns and would have all of the import rows for every day.My question would be this: I want to be able to have an integer Primary Key unless there is a better idea. I could make the STAGE table use an auto-incremented value for the key. Then, when I load the import table which is truncated every day, I could take the NEXT value of the key from the STAGE table and increment by 1.
Let's say the last value in STAGE is 1000, then the next value that would be in IMPORT would be 1001 and incrementing up. Then these would be added to the STAGE table with the associated keys. There is no chance of anyone or anything else adding to the STAGE table any other way.
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Sep 11, 2015
How do I correctly populate a fact table with the surrogate key from the dimension table?
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Aug 16, 2007
Hi,
I use lookups to map surrogate of level 1 dimensions to my fact tables in SSIS.
But how to handle a level 2 dimension with a ValidFrom and a ValidUntil date field?
I do not use an IsCurrent column, because this could problem with late arriving facts.
- In dts I used an SQL statement like this:
update SA
SET SA.DimProdRef = Dim.RecordID
FROM SAWarenEingang SA, DimProd Dim
where SA.ProduktNumber = Dim.ProduktNumber
and SA.ArtikelkontoBewegungsdatum between Dim.ValidFrom and Dim.ValidUntil
Now in SSIS I want to handle the whole thing in the data flow without using a staging table:
- Using Lookups: I would have to pass the date column for each inside the fact table into the lookup. That does not work.
- Using Execute SQL in the data flow: would be very slow, because the statement will be executed for any line in the dataflow
Any ideas?
Best regards,
Stefoon
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Nov 5, 2015
I have dimension data like this
persn_key persn_id address is_active updated_date
1 10 NYC 0 2015-11-04 14:19:54.817
2 10 Chicago 1 null
and Fact table like
fact_key persn_key units_purchased
1 1 10
persn_key is the surrogate key between tables.
My question here is as the dimension has SCD type 2 on it and every time when there is a change the persn_key gets a new key value but the fact table still points to oldest key.how to update the surrogate key on fact table to the current key value? As per the requirement fact surrogate key must be pointing to current active record on the dimension.
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Sep 23, 2006
I'm just now learning both SQL and ASP.NET, and I cannot seem to figure out how to build my data structure. I believe the answer to my problem is a composite key, but I cannot seem to get it to work. Here is an example. My database is of recorded dances, with exact locations within a ballroom. I believe I need 2 tablesTable #1 - DanceTableColumns: DanceID, Name, Description, TagsTable #2 - StepsTableColumns DanceID, StepID, longLocation, latLocation, Action, DescriptionWithin my ASP.NET application I want to be able to enter data about a dance, including metadata and a series of steps. The Dance and metadata content to be stored in DanceTable, and the series of moves stored in the StepsTable. I want the steps to be IDed as 1, 2, 3, 4...x with the first step being labled 1. and I want each dance to have it's own unique ID (DanceID). Right now I'm using "ExecuteNonQuery()" to add my data to my SQL database, and when I add new steps to the StepsTable SQL just finds the largest ID within StepID and increments it by one. So my steps are labeled as:Dance1:Step1, Step2, Step3, Step4Dance2:Step5, Step 6, Step7What I really want is (or I think what I want is) is a composite primary key.Dance1:Step1, Step2, Step3, Step4Dance2:Step1, Step2, Step3That way the StepID is used as both a primary key and it indicates the position within the dance. I guess I could just use a standard SQL table, let SQL auto generate StepID's and then add a new column called something like "StepNumber", but it just seems goofy to be generating a stepID and never using it. With composite keys (If I understand them) each step would have a unique key as a combination of the DanceID+StepID (AKA Dance 345, steps 1-10). I pull up data by searching for dances, and then sort by StepNumber, and those should all be unique...if I can figure out how to build them.
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Nov 9, 2006
I have a table with a composite key formed by the unique combination of columns w, x, y, z
I'm trying to write an INSERT statement along the following lines
INSERT INTO myTable
(SELECT w, x, y, z FROM someTable) t1
WHERE (this is the part I'm stumped on - where the unique combination of w, x, y, z is NOT in myTable already)
Help would be appreciated. Can you use the NOT IN keyword on composite values?
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May 29, 2008
How can I create a composite key (two primary keys for one table) using SQL Server 2005 Management Studio? Can I do it using the GUI, or do I have to write SQL code to do this? Thanks
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Apr 19, 2004
Made an interesting discovery today - a column of data type Bit is not allowed to participate in composite key. Rather surprised.
I have a certain unique code that exhibits 2 unique states, which rendered the use of the boolean column, so the uniqueness goes <code>-1 and <code>-0. Is there any 'hack' so to speak to avoid using a Tinyint for the boolean column instead?
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Jun 10, 2005
Hi,
Suppose there is a composite index on a table, and in includes, for example 3 columns.
If I do a select using one of those three columns, will the select use the composite index? Will it aid in retrevial or should I create an index on the
individual column.
any thoughts on this would be appreciated.
thanks
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Sep 24, 2004
Can someone help me create a composite key on ms sql server through the enterprise manager?
Thanks,
Laura
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Feb 11, 2005
Hi folks, i need an advise.
I've a gerand table customers_orders table with customer_id and order_id.
Whenever we have to find orders, for customer, this table is involved. Hey; i know u'll be angry y the heck this gerand exist but i've to blame the older dudes then.
Now this table has composite clustered index; CUSTOMER_ID+ORDER_ID.
The tables have grown over GB size; i see HASH INNER JOIN rather than MERGE for the GEREND and CUSTOMER table join.
Is it good to use composite clustered index; or should i clustered one the columns in the GEREND and other to normal index. What performance impact it could be.
Howdy!
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