Link Table Versus XML Column For One-to-many Relationship
Jun 10, 2007
I am designing a database schema where several tables have one-to-many relationships to records in other tables. One way to implement it is to create a link table for each pair of tables that have a relationship:
identity
Table1_ID
Table2_ID
1
12
9
2
12
15
3
18
42With the SQL 2005 support for the XML data type, there is the possibility of storing the IDs in an XML column. The XML stored with a record (equivalent to record 12 from the above example) might look like this:
<Links>
<Table2_LinkType>
<ID>9</ID>
<ID>15</ID>
</Table2_LinkType>
<Table8_LinkType>
. . .
</Table8_LinkType>
</Links>The XML column method has the advantage of not requiring that a separate table be created but does not enforce referential integrity. The link table method has the advantage of allowing constraints to enforce referential integrity but has the disadvantage of requiring the creation of a separate table for each pair of tables having a relationship and joining to an additional table has performance implications. Implementing standard Add, List and Delete operations for the link table method is straightforward. As a test and to familiarize myself with the new XML features, I created Set, List and Delete stored procedures for the XML method. Both methods will work.
In deciding which method to go with are there any other issues I should be considering besides database integrity, complexity and possible performance issues?
From the standpoint of best practices and coding standards is one method preferred over the other?
Here is some additional information. The data set I will be working with has table sizes numbering in the hundreds of thousands. Any given record will only be linked to at most a half-dozen records in any other table.
I searched on-line for information and I was able to find plenty of good articles discussing how to use the new XML data type in SQL. However, I was not able to find any information on when not to use the XML data type over equivalent joined-table methods.
When trying to link to an SQL table in Access 2003, the software appears to be malfunctioning.
The sequence of events is File - Get External Data - Link Tables - Files of Type: ODBC Databases().
The Problem: On two of my computers, the select data source window does not pop up, preventing me from linking to any ODBC data source.
Observations: This function has worked normally in the recent past and works on other computers running Access 2003. One difference between the computers working and non-working computers is Norton Antivirus 2006 (recent upgrade).
Has anyone experienced anything like this? What's going on?
In a previous post "Could #TempTable within SP cause lock on tempdb?" http://forums.microsoft.com/msdn/showpost.aspx?postid=2691763&siteid=1
It was obvious that we have to limit the use of #Temp table to a minimum. Let assume that some of the temp tables are really difficult to replace and we have to live with them.
Would it be easier on tempdb if the #TempTable is replaced by a table variable? Or do they all end up in tempdb?
I need to concatenate a field from certain number of rows. I created a function to return the concatenated value which will be a part of another view/procedure to be used for reporting purposes.
final woorkNoteAll will be a part of a query in another view which contains many other fields.
Here's the function. I'm passing an ID and based on that ID, the function returns a string. However, when I tested the function it's giving me a null.
/* --Calling syntax:: Select dbo.getIncidentNotes(187714) as 'Notes' --Function to get all the latest notes for an incident */ CREATE FUNCTION dbo.getIncidentNotes(@iIncidentID int) RETURNS varchar(8000) AS BEGIN DECLARE @allnotes varchar(8000) DECLARE @seqnotes varchar(255) DECLARE @seqnum int DECLARE @counter int SELECT @counter=1
SELECT @seqnum = max(iseqnum) from dbo.frs_weekly_prospect_status2 where iIncidentId=@iIncidentID
WHILE (@COUNTER <=@seqnum) BEGIN SELECT @seqnotes = workNoteALL from dbo.frs_weekly_prospect_status2 where iIncidentId=@iIncidentID and iSeqNum=@counter SELECT @allnotes = @allnotes + @seqnotes SELECT @COUNTER = @COUNTER + 1 END --While Begin RETURN @allnotes END
Can someone please tell me what's wrong with the code?
I've got a dilemma which I hope someone has a solution to.
Let's say we're building a data mining model to predict aircraft reliability. In the training table we've got a column (among many others) with a unique aircraft ID, and then a column for the type (737,747) and then a column for the series (100,200,300). I.E. A 737-800 series would be "737" and "800".
There is in essence a parent-child relationship between these 2 columns. 737's should share a common set of reliability factors, and then those factors might be further defined by the series number (for instance, the 737 might have very reliable radar except for the 500 series). The series is analogous to what model year a car is. What I want to make sure doesn't happen is for the system to correlate a 747-400 and a 737-400 because they are the same series. They are totally independent if the model number is different.
My only idea was to merge the columns and have a single value "737-100". But it would seem then that the model won't have any idea that a "737-100" and "737-200" should have a lot more in common than a "737-100" because the values will be completely different.
I was hoping to find some sort of parent-child hint in the column properties but found none.
What solutions have other people tried? It sure seems that there should be an elegant solution for something like, but I'm missing it.
I am trying to create a new mining structure with case table and nested table, the case table (fact table) has alread defined the relationships with the nested table(dimension table), and I can see their relationship from the data source view. But why the wizard for creating the new mining structure showed that message? Why is that? And what could I try to fix it?
Hope it is clear for your help.
Thanks a lot for your kind advices and I am looking forward to hearing from you shortly.
I want to be able to return the rows from a table that have been updated since a specific time. My query returns results in less than 1 minute if I hard code the reference timestamp, but it keeps spinning if I load the reference timestamp in a table. See examples below (the "Reference" table has only one row with a value 2014-09-30 00:00:00.000)
select * from A where ReceiptTS > '2014-09-30 00:00:00.000'
select * from A where ReceiptTS > (select ReferenceTS from Reference)
When I need to perform an update against multi-million row table Itypically specify @@rowcount, to reduce locks.e.g.set @@rowcount 1000while exists (select * from myTable where col2 is null)update myTableset col2 = col1 + 'blahblah'where col2 is nullHowever, my boss' script does something like this. I think it works OKbut it seems overly complicated to me. Any thoughts?while exists (....)begin traninsert into #tableselect ...update myTableset ...from myTable join #table ...(@numberOfRows is a counter variable, tracking #rows that have beenupdated since last batch)if @numberOfRows > 1000begincommitbegin tranendend
Hi,I am expanding our data warehouse solution with new filegroups onseveral subsystems.I want to know which idea is better!- create clustered indexes on tables to 'move' them to new filegroups- create these tables on the new filegroups.The background of this question is as follows:- we want the whole data on the new filegroups- we want to know if there is any difference in performance between the2 solutionsThanks in advance,Danny
I have 2 excel tables files.One table has info about sales by country, by model, by date...and the other table has units by date.Obviously, the common key is "date"....and by creating a relationship, I can add "units" to my combined resulting table.However, I can't create the relationship. Excel keeps telling me: "the relationship cannot be created because each column contains duplicate values. Select at least one column that contains only unique values".
I realize this a Transact SQL forum. If there is another forum more appropriate, please let me know. I want to think about the best way to begin to set up this database with respect to the column that will link these tables together. The info below is what has been given to me as my client's list of values/info she would like to include. Here is my first pass, knowing that the ID columns need to be fixed. Thank you! http://www.hazzsoftwaresolutions.net/db_diag.htm
Excuse my illiteracy in this subject, I just learned about this yesterday, I managed to create a report by using business intelligence report wizard, and when I preview it seems that I can view the fields that I wanted to view.
But in addition to that I also want to add hyperlinks to some of the fields, because I am planning to embed the whole report in a web page. For example if I go on the field that I want to add hyperlink and right click->properties->navigation tab->Jump to url, I thought that I can handle it. Actuall it works fine if I link it to http://www.microsoft.com but let's assum e the name of the field is ID, and you want to link to http://somewebsite/somepage.aspx?id= (id in that cell), how can I achieve this parametric behavior, actually I tried right click cell->properties->navigation tab->Jump to url, and filled url text box http://somewebsite/somepage.aspx?id=&(concatenation operator)=Fields!ID.Value but what happens is instead of evaluating the value of ID field, it takes expression as text as text and that's why it links to totally wrong url. Is there a way to get around this problem.
And can somebody suggest me a detailed tutorial on programmatically using reports in .net web applications using c#.
However, the userelationship function does not override the active relationship between Operation & Advice and so the measure is limited to Advices directly filtered by the Operation table.
If I delete the relationship between Operation and Advice, then the measure works as expected i.e. Operation indirectly filters Operation Commodity which filters Advice.
Hello, I created some SQL 2005 tables using Microsoft SQL Server Management Studio. I need to get the script code of those tables. I was able to do that by right clicking over each table. But how can I get the code for the relationships between the tables? Can't I create relationships between two tables by using T-SQL? Thanks, Miguel
Hi I have two tables: 1.) Operator-OperatorID{PK, int, not null}-OperatorName{varchar(100), not null}-Enabled{bit, not null}-PasswordChange{bit, not null}-BirthDate{datetime, not null} 2.) Password-PasswordID{PK, int, not null}-Password{varchar(50), not null}-ExpirationDate{datetime, not null} I'm not sure how to design and layout these two tables. The layout of these two tables is completely flexible as the application has not been deployed. I'm open to any good suggestions. For each Operator I want to stored up to 3 previous passwords plus their current password. The password change field is so that if the operator's password expires or gets reset, they will be forced to enter a new password. This is a simple internal company application, so password encrypting is not necessary. The ExpirationDate indicates the date that the password will expire.
Why is it not possible to define more than one relationship per table?
i have a primary table that i would like to cascade deletes to 2 other foreign tables in 2 separate relationships. why can't i do this and what are my alternatives?
i ve got a database that has a table...that table has a relationship between its primary key,and another field,actuelly i did it for doing menus and sub menus,so each menu has an ID say menuID and it has DEPTH and parentID which is the menuID of the parent...the problem is that i can not use "Cascade update Related Fields" or "Cascade Delete Related Records" which are really necessary ...for example when deleting parent ,not to have a child lost :)i hope i ll have an answer soon,and thanks in advancedPS: i am using MSSQL 2000 evaluation
We have two tables. Users and Projects and there is a many-to-many relationship.Ex. A user can be assigned into multiple projects.For the relationship table, should the table name be UserProjects or ProjectUsers?Also should it be singular or plural? (ex. UsersProjects or ProjectsUsers)?
Hi, I come back again. Can anyone help me to create table with many-to-many relationship. Here is my three tables tbl_Networks ( NID int identity(1,1) primary key, NetworkName nvarchar(256) )
tbl_Categories ( CID int identity(1,1) primary key, CateName nvarchar(256), NID int )
tbl_Sim ( SID int identity(1,1) primary key, NID int, CID int, NameOfSim nvarchar(256) ) My problem is 1 value in tbl_Sim may have multiple values in table tbl_Categories and vice versal. And I don't know how to organise them
I have 3 tables I am trying to relate for a music player. I was following the example in the msdn however, my relationships do not seem right. Here are tables i want to relate:
So the main idea here is that the foreign keys are recordingId and artistID. So what i did is created the 3 tables and then make a diagram to create the relationships. I then was reading this post:
What i want to do is use 2 different text boxes lets say and as i move from the records in the Record_table (2) the corresponding artist will change with it. However in the dataset the relationship looks like this: Artist -> Recording -> Track.... inorder for me to get this relationship to work correctly i have to change all the relationships in the dataset diagram. This way the dataset would look like this: Track -> Recording ->Artist. This way i can use the 2 bindings to reference each other as stated in the link above. why doesnt the relationship of the database know this already? why do i have to change the relationship in the datasets.
I have two tables: ads and categories. I have an existing relationship: categories.id (PK) and ads.categoryid (FK). Now I want to create additional relationship with categories.id (PK) on ads.SecondCategoryID (FK). When I try to save it in SQL Manager I get the following error: - Unable to create relationship 'FK_classifieds_Ads_classifieds_Categories2'. The ALTER TABLE statement conflicted with the FOREIGN KEY constraint "FK_classifieds_Ads_classifieds_Categories2". The conflict occurred in database "mydb", table "dbo.classifieds_Categories", column 'Id'.
I am using tables with recursive relationships extensively. For example the table tbComponent has a primary key called Co_ID and a foreign key called Co_Co_ID which references the field Co_ID. This allows a component to have unlimited child components, and each child component can have an unlimited number of tiers of children. I have a few question for which I have seen no documentation on.
1. How can I create a view or a SP that will return a component record and all of its children and children's children records down to the last/lowest child record?
2. I need to be able to do a search in this table. Example:
Table: tbComponent Columns: Co_ID Integer Co_Co_ID Integer Co_Name Text Co_Attribute Text Co_Category Text
Note: the data for Co_Category comes from a lookup table with also has a recursive relationship to itself where a category can have an unlimited number of tiers of children categories.
A typical group of records could be something like this:
Co_ID Co_Co_ID Co_Name Co_Attribute Co_Category
1 1 Car Blue Ford 2 1 Body Steel Parts 3 2 Door Front Parts 4 3 Invoice April 1 1999 Accounting
Ok, say there is over a million records in this table. Say I want to query this table and return all of the invoices for cars between March 1 1999 and May 1 1999. Say for example that there are less records where Co_Name has a value of Car then there are records with a value of Invoice, so logically I would set some kind of criteria to limit only invoices with where Co_Name = "Car". That's easy, I can return a result set of all the records Where Co_Name = "Car" and I can hold these in a view or a temp table. Now I need to query this View or temp table and see if it has any children records records Where Co_Name = "Invoice" . The problem is that the Invoice child could be a child record directly under the "Car" record, or 10 levels of children records down. The logic for this would be:
If Co_Name = "Car" Then Select * Where Co_Co_ID = 1, then take all of those record's values in Co_ID and run another statement Where Co_Co_ID = X and so on until there are no more children to search. If any of those records have a value of Invoice in Co_Name then return them.
Please don't give any speeches on Normal Relationship Database design suggesting a typical design using something like a Car table, a parts table, and a invoice table. I used the example above to demonstrate the dynamics of doing a search on a recursive relationship. I understand relationship theory and a recursive relationship is what we need to use in our situation.
Below is my sample data of my table named "Groups"
Code: with Groups as ( select 1 as GroupId,'Oracle' as GroupName,0 as IdParentGroup union all select 2 as GroupId,'Microsoft' as GroupName,0 as IdParentGroup union all select 3 as GroupId,'IBM' as GroupName,0 as IdParentGroup union all select 4 as GroupId,'SunMicrosystem' as GroupName,1 as IdParentGroup union all select 5 as GroupId,'peoplesoft' as GroupName,1 as IdParentGroup union all select 6 as GroupId,'mysql' as GroupName,1 as IdParentGroup union all select 7 as GroupId,'Nokia' as GroupName,2 as IdParentGroup union all select 8 as GroupId,'EShop' as GroupName,2 as IdParentGroup union all select 9 as GroupId,'Meiosys' as GroupName,3 as IdParentGroup union all select 10 as GroupId,'UrbanCode' as GroupName,3 as IdParentGroup ) select * from groups;
Expected result:
Code: with ExpectedResult as ( select 'Oracle' as GroupName,'SunMicrosystem' as SubGroup union all select '' as GroupName,'peoplesoft' as SubGroup union all select '' as GroupName,'mysql' as SubGroup union all select 'Microsoft' as GroupName,'Nokia' as SubGroup union all select '' as GroupName,'EShop' as SubGroup union all select 'IBM' as GroupName,'Meiosys' as SubGroup union all select '' as GroupName,'UrbanCode' as SubGroup ) select * from ExpectedResult;
some sample query to how to achieve this parent-child has the same table.
I am fairly new to SQL and I am currently trying to createa SQL table (using Microsoft SQL) that has a recursiverelationship, let me try to explain:I have a piece of Data let's call it "Item" wich may again contain onemore "Items". Now how would I design a set of SQL Tables that arecapable of storing this information?I tried the following two approaches:1.) create a Table "Item" with Column "ItemID" as primary key, somecolums for the Data an Item can store and a Column "ParentItemID". Iset a foreign key for ParentItemID wich links to the primarykey"ItemID" of the same table.2.) create separate Table "Item_ParentItem" that storesItemID-ParentItemID-pairs. Each column has a foreign key linked toprimary key of the "Item" Column "ItemID".In both approaches when I try to delete an Item I get an Exceptionsaying that the DELETE command could not be executed because itviolates a COLUMN REFERENCE constraint. The goal behind these FK_PKrelations is is that when an Item gets deleted, all childItems shouldautomatically be deleted recursively.How is this "standard-problem" usually solved in sql? Or do I inned toimplement the recursive deletion myself using storedprocedures or something ?
I want to create a 1-many relationship. Parent table has a primarykey, child table has no primary key. The child table does have anindex with all four fields of the parent's PK. How can I do this?Thanks, Bob C.
I am having challenge to update the redemption table from the multiple card activation table. I want to update the redemption table with the activation date closest to the redeem date.
For example: Redeem date 20071223, I need to update the top row Date, Year, Period fields from the Card activation table.
Redeem date 20071228, I want to refer to the second row in the Card activation table date 20071228. Redeem date 20080316 or later, I want to use the last row in the card activation table date 20080316.
How to modify the update query to select the right activation row accordingly?
Below is my partial code I used but it always pick the 20071223 date to update my redemption table.
CREATE TABLE #Card ( [CardNumber] varchar(20) ,[ Date] int ,[ Year] int ,[ Month] int ,[ Period] int )
I've got a table that includes:CREATE TABLE [dbo].[Content] ( [Id] int IDENTITY(1, 1) NOT NULL, [ParentId] int NULL, I'm wanting to make sure that a ParentId must be in the table as Id someplace else. When I try to do it by making it a foreign key get the error: --------------- SQL --------------- ALTER TABLE [dbo].[Content]ADD CONSTRAINT [Content_fk3] FOREIGN KEY ([Id]) REFERENCES [dbo].[Content] ([ParentId]) ON UPDATE NO ACTION ON DELETE NO ACTIONGO ---------- ERROR MESSAGE ---------- There are no primary or candidate keys in the referenced table 'dbo.Content' that match the referencing column list in the foreign key 'Content_fk3'.Could not create constraint. See previous errors.
Any ideas?
ALTER TABLE [dbo].[Content]ADD CONSTRAINT [Content_fk3] FOREIGN KEY ([Id]) REFERENCES [Content].[dbo] ([ParentId]) ON UPDATE NO ACTION ON DELETE NO ACTIONGO
Below is my sample data of my table named "Groups"
with Groups as ( select 1 as GroupId,'Oracle' as GroupName,0 as IdParentGroup union all select 2 as GroupId,'Microsoft' as GroupName,0 as IdParentGroup union all select 3 as GroupId,'IBM' as GroupName,0 as IdParentGroup union all select 4 as GroupId,'SunMicrosystem' as GroupName,1 as IdParentGroup union all
[Code] ....
Expected result:
with ExpectedResult as ( select 'Oracle' as GroupName,'SunMicrosystem' as SubGroup union all select '' as GroupName,'peoplesoft' as SubGroup union all select '' as GroupName,'mysql' as SubGroup union all
[Code] ....
How to achieve this parent-child has the same table.
