Composite Primary Keys
Feb 25, 2005
Is it possible that a composite primary from table A to be a foreign key in table B?
I have two tables: A and B. The A has some personal details such as first name, surname, phone number, etc.
Since no personal ID is given in my project, I am thinking to use first name + surname as the primary key of table A. But when I wanted to make the relationship between A and B (in B I need to use these 2 name fields as the composite primary keys, too) and ticked the option “enforce referential integrity”, an error message prompted out said it could not find the only primary key in table A.
What should I do with this? Or it is impossible to have a composite primary key to be foreign keys (but also primary) in another table?
It will be great if someone could answer this!
Thanks!
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May 5, 2005
I've noticed that the great and the good all seem to recommend not using composite PKs. Does that even go for join tables in the middle of a many-to-many relationship? Not sure I see what's to be gained by adding an ID and making that the PK.
Any comments?
Dave
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May 17, 2007
I am creating a bridge table to get rid of redundant data. I am doing it by making a composite of the primary keys from the two tables I am bridging.
The error message when I get to a certain point is "You cannot add or change a record because a related record is required in table tblMachCent." Both the numbers I am using to create this composite key are in the tables necessary, so I am not sure why I am getting this problem. Any suggestions??
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Dec 5, 2005
I have recently started a new project, on one of my tables i have a composite key for my primary key. However when i create a relationship using one of the fields in the primary key i can't "enforce referential integrity". Every time i try i get the message "No unique index found for the referenced field of the primary field"
can any one help
Mindy
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Oct 6, 2007
Many to Many
I have a basic question, I know for a fact that all many to many relationships have to be broken into two one to many relationships using a junction table. However does that mean it is (a must )to have the two foreign key of the parent tables have to be the (primary composite key) of the junction table.
For example, let’s say I have 5 tables that I need to establish many to many relationships between them. Is it correct to establish a junction table with all 5 foreign keys of the parent tables as composite primary key in the junction table to!
Hope the above making sense!!! :confused:
Many thanks :)
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May 13, 2005
Can Access deal with Composite Primary Keys? or will it only let you assign a single attribute key?
If it does allow you to create composite primary keys, how do you go about doing it?
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May 12, 2005
I need some help with developing a certain aspect of a db. I need to track the equipment list of clinics. The equipment list doesn't really change (it has 5 possible values though each clinic may only have one to all 5 of them). The db is also to track who the manufacturer is.
I was originally going to do a three piece composite key consistenting of the clinic id, the equipment id and the manufacturer id with quantity as the non pk field. Or the other possiblility that I can see is just using an autonumber as the pk with clinic id, equipment id, and manufacturer id as fk's with qty as the non-key field. So what do you think? If you can put in explanation why your suggestion would work, that would be appreciated as I'd like to increase my knowledge base on this stuff.
If I haven't made my problem clear, I'm quite willing to provide more info.
Thanks,
scratch
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Oct 3, 2007
Hi,
I am trying to join 2 tables with composite keys - each of them have the same 4 columns as part of its key - date/person/problem/date sent.
Table 1 has 5 columns (4 key columns + 1), Table 2 has the same 5 columns plus 1 additional column (Comments).
I am trying to match the Comments column in Table 2 to Table 1 and show the output in another table.
Currently, I've related the 4 columns in each table to each other, each relationship defined as including all records from Table 1 and only the records from Table 2 where the fields are equal.
In the fields, I have 5 Columns from Table 1 and the last column (Comments) from Table 2. When I run the query, I get all the records from Table 1, but not all of the Comments that match from Table 2 are shown.
Any Ideas on how to improve this link?
Thanks!!!
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Sep 9, 2005
I have a rather interesting situation involving creating a primary key. Basically I have two tables.
Table 1
Date, Customer, Part Number, Work Order, Qty tested, qty failed, tech name
Table 2
Defect, reference, quantity(defect), defect cause, part number, work order
The ideal relationship I want to create is that for every Table 1 there are multiple table 2. Regular one to many relationship. The problem is that in the first table it is possible and probable that there will be duplicate records because of the process. The test parts by individual carts, but often they're exactly the same parts with same work orders and same everything else. How should I go about doing this. I don't want to just create an autonumber for each record if possible. Any suggestions?
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Jun 2, 2013
Composite Primary Key in Ms Access 2010. I shall try and explain my tables in detail. So my first table is "Client Database" where the field "Buyer" is primary key. This is connected to my next table "Project Database" which has fields such as Work Order #, PO #, PO Date , Buyer etc where Work Order # is the primary key. Finally "Projects Database" is connected to Order information. Now the problem is until now, I always had 1 PO # for each Work Order #. However now I am facing a situation where my client has clubbed multiple PO #'s for the same Work Order #. I need to trigger the Primary Key Violation only if both the Work Order # and the PO # are the same.
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May 29, 2012
I am trying to set a primary key on two fields. the problem is that the one field is null for some records. They will eventually fill them in. However, because it is null now it will nowt let me set it as a primary key. I tried setting the field, in the properties, with a default value; but it would not take it.
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May 16, 2005
I am trying to run a query that links to tables, orders and invoice together. I am pulling fields from each table, with a relationship between Order# which is found in both tables. The only problem is, order# is a composite key in the order table and strictly a foreign key in the invoice table, referenced through a combo box drop down. When i attempt to create a query, it will not run. (Also will i find a similar problem with my combo box reference?) Any ideas on how to create a query would be appreciated.
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Sep 23, 2014
I have a question concerning the automatically sequential numbering of a primary key as part of a composite primary key.
Tbl_treatment:
ID=numeric field (also in tbl_pt and in tbl_tumor)
Tumornr=numeric field (also in tbl_tumor)
Treatmentnr=numeric field
[ID] and [tumornr] are fixed and i would like to automatically number [treatmentnr] per [ID] AND [tumornr] in a way that the output will look like this:
1001 1 1
1001 1 2
1001 1 3
1001 2 1
1001 2 2
1001 3 1, etcetera.
However, when i use the SQL-formula below my output looks like this. It seems as if the function is not properly taking the composite primary key of [ID] AND [tumornr] into account or not finding the true max value:
1001 1 1
1001 1 2
1001 1 3
1001 2 2
1001 2 3
1001 3 3, etcetera.
If (DCount("[treatmentnr]", "Tbl_treatment", "[ID] = " & Me.ID & "" & "AND [tumornr] = " & Me.tumornr & "")) = 0 Then Me.treatmentnr = fRowNum(False)
Else Me.treatmentnr = (DMax("[treatmentnr]", "Tbl_treatment", "[ID] = " & Me.ID & "" & "AND [tumornr] = " & Me.tumornr & "")) + 1
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Nov 28, 2005
I was wondering if anyone would be able to help me? I have two tables which can be linked together as they both contain a field called Company Name. However, in one of the tables I want Company Name to become my primary key but this field contains duplicates. How can Isolve this so that I can still link my two tables together?
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Jun 26, 2007
I have two tables :
schema with :
schema-id, Autonumber, primary key
name, text
and a table regel :
regel-id, Autonumber
class a, number (lookup from a table)
class b, number (lookup from a table)
schema-id, Long number
they are linked 1:n. A schema can have many regel's.
I want to make a form of schema and have that form contain a subform with regel's in it. The subform can be shown as a datagrid.
Now here's what I do.. I start the form wizard and select both tables. The wizard takes me to creating what I want and it works too. I have a main form schema and a subform with regel's.
Now I have a problem :
The regel fields (class a and class b) can have only three possible values. And I don't want that the combination of these two fields can be the same.
I'v thought about making these two fields the primary keys of regel, but that doesn't work. It works for one record of schema, but when I navigate to a next record of schema, I can't make all combinations of class a and class b over again. It's like I used the combinations in the preceding record of scheme. Then I tried making three fields the primary key, namely class a and class b and regel-id. Didn't work either. What I need is a primary key on the combination of schema-id, class a and class b. But I don't know how to do that.. after all, schema and regel are seperate tables.
I want to be able to make for every schema record all possible combinations for regel records.
How do I do that?
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May 1, 2005
Hello all,
I am re-working an old database that 'grew up' the wrong way. It is a medical patient database and has 4 main tables. Primary key of main data table is Medical Record number (MR#), a user entered field (I know...). This links to 3 other tables: Diagnoses (indexed by MR# as well, 1-to-1 relationship with main table), Consults (indexed by a compound key of MR# and date, 1 to many relationship), and Procedures (indexed as well by MR# and date; 1 to many as well).
Here is my plan, and I want to know if I'm going to go about it the right way:
I will first delete the relationships between these tables.
I will then give the main table an autonumber field called PatientIndex, and each other table their own autonumber (DiagnosisIndex, ConsultIndex, ProcedureIndex). I will also give each of the other 'daughter' tables a PatientIndex field as well. I will populate the PatientIndex fields of the daughter records with a VBA routine that matches their MR# with the MR# in the main table, and then inserts the corresponding PatientIndex.
Now that each table has no relationships, and has all the right fields, I suspect Access will allow me to change the Keys for each table, and create new relationships, and it should all work cleanly. The goal is to have each table indexed by an autonumber field that is unrelated to user entry, and to link them by the Primary key.
Does this sound like the right approach? As to why do this if it works OK, it's a matter of maintenance. It's simply too buggy as it stands, and it's torturing me. Will my plan work without crashing the db?
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Feb 28, 2005
I made a database that was working fine. It was only after I had finished the database, and data was being entered, that I was informed that the field I designated as the primary key would not work. Origanally, I used 'OffCit' as the single primary key. Now they tell me that one 'OffCit' can be entered several times for different reasons. To solve this, I thought about using autonumbers but have been told, and seen, that this may not be a good idea. So, I am trying to use multiple primary keys. So far I have had no luck. I have attached a screen shot of the tables and relationships. I have 'OffCit', 'AreaofLaw', and 'EffectiveDate' as the primary keys. The same 'OffCit' and 'AreaofLaw' will be used several times in different records. That is the reason for the third primary key. I am wondering if I have set this up right or if there is something I overlooked. Perhaps someone has an idea that may work better. Thanks for any input.
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Sep 13, 2005
I have the following table:
YieldID |ProductID | Year | Month| Yield
I want to make sure that it is not possible to insert the same date (so, year and month together) twice for each productID. But at the other hand, it should be possible to insert the same date but then for different productIDs. How can I make sure that Access does this? Can I use (multiple) primary keys to enforce this?
Thank you,
Stacey
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May 21, 2006
Hi
I have tried searching the forums, but couldn't locate any relevant information. I have an assignment at the moment and am meant to have 8 tables in my data base, two of which are 'User' and 'Hardware' which have the following fields:
USER:
UserCode (Primary Key)
UserFirstName
UserLastName
DepartmentCode
HARDWARE:
HardwareCode (Primary Key)
HardwareName
VendorCode
PurchaseDate
Now I am meant to have another table called 'Hardware Config' consisting of the Primary Key fields from the two tables above, and they are both meant to be Primary Keys in this table.
I have been able to make the 'Hardware Config' table, but I don't know how to make more than one Primary Key... any ideas?
Thanks in advance - dragonfly :o
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Jul 31, 2007
SOLVED: Hows it goin?I need to assign a second primary key to a table involving three fields (Student Number, Subject Code and Average). I have to make Student Number and Subject code the primary keys. Any help would be appriciated.
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Oct 6, 2007
I have a table that has the following fields: Symbol, DeliveryMonth, DDate, Close. This table has information for a large number of different commodities. I am hoping to run a query against the table and find breakouts. I am working on the actual query but my question is this: If I have only one table do I need to have a primary key? There will be no relationships established so what is the need for a primary key unless you plan to link tables together? If it is always a good idea to have a primary key then I will have to have the Symbol, Delievery Month and the DDate together be the key since without all three there would be duplicates. Each symbol has many different deliveryMonths, each DeliveryMonth has many symbols, and each date has many Symbols. SO it takes all three together to get a unique value. Will having a primary key in this scenario help me with writing queries? I appreciate all of your wisdom in explaining how this table should be organized. Thanks:)
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May 3, 2005
I have a table (call it Table1) with a primary key that is a number and one other text field which is what the user would recognize the field by.
Another table (table 2) looks up to table 1. And yet another (table 3) looks up to table 2. I want the text name to show in the lookup list of Table 3 - NOT the number.
Right now, when I look at the sql results in the lookup field for table 3, the text appears rather than the number. But when I open table 3 and try to use the lookup list, the number appears.
Any ideas how to fix that? Do you need more details and sql?
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Jul 9, 2006
Looking at a database that someone wlse has created I see that numerous tables have mulitple primary keys. How is this possible? If i try and allocate a primary key it will only let me do it for one field.
I think what I actually want to do is create composite keys but if I set the key then put it to duplicates allowed it says that the primary key is not allowed. Am I mixing up indexes and keys???
How do you assign a composite key
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Mar 21, 2013
I have a table where each record is unique if at least one of three variables is different. The three variables in my case are each integers and are: YearRouteSegment.
Now each of these individual variables allows (and has) duplicates, but if the thing is working right, no pair of records in this table should have all three of these variables with identical values. Is this table a candidate for using multiple primary keys?
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Jun 6, 2007
I'm having lots of erratic problems with our Access database. Back end tables on the server, front ends on workstations. Running Windows 2000 server, Access 2003 SP2 on Windows XP SP2. I'm not the network administrator so don't have much detail on network. For instance, the back end is 'losing' relationships between tables, with the primary key on the 'one' end of a 'many' relationship disappearing - the relationship link between the tables also disappears. Other errors are:- erratic problems with indexes which are sometimes fixed with a compact / repair, sometimes not- data on forms disappearing- data on forms appearing in the wrong field- queries that ask for parameter input twice when only programmed to so once- sorting orders suddenly going wrong way round - inability delete a record via a form, caused Access to completely crash with Microsofts 'sorry unrecoverable error' message. To fix the query problem, I created a blank query and imported the old one into it, problem solved. But what caused the old query to act weird in the first place?To fix the inability to delete a record problem, I created a whole new blank database and imported everything into it. But what caused the database to repeatedly crash? The suddenly missing relationships I have no cure for. I'm at the end of my tether - can't figure out any pattern to this. Any suggestions? Network errors? Read / write on server? Disk space / fragmentation? Fundamental problem with the database?Any help much appreciated.Sorry if this post should have been in the tables forum.
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Feb 14, 2005
I can create multiple primary keys for a table MANUALLY (by highlighting several field then pressing the key icon)
BUT I cant recreate it by code.
HELP.
Set NewFld = tdfnew.CreateField("TaskID", dbLong)
Set idxNew = tdfnew.CreateIndex("TaskIDIndex")
idxNew.Fields.Append idxNew.CreateField("TaskID")
idxNew.Primary = True
tdfnew.Indexes.Append idxNew
tdfnew.Fields.Append NewFld
tdfnew.Fields.Refresh
Set NewFld = tdfnew.CreateField("SubzoneID", dbLong)
Set idxNew = tdfnew.CreateIndex("SubzoneIDAIndex")
idxNew.Fields.Append idxNew.CreateField("SubzoneID")
idxNew.Primary = True
tdfnew.Indexes.Append idxNew
tdfnew.Fields.Append NewFld
tdfnew.Fields.Refresh
I am getting an error, there is already a primary key.
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