Tables :: One Primary Key To Multiple Foreign Keys In The Same Table?
Aug 29, 2013
Right now, I have 4 related tables. There's a table with companies, one with people involved with companies, a table linking the two by having foreign keys of the company number and people names, and a table that indicates directors and their alternates.
Since there's a one-to-many relationship for companies/people to company-peopleID (A person can run multiple companies, a company has multiple directors, it's easier this way), a person's name can appear multiple times, as can a company, within that table.
In a company, a director may or may not have 1 and only 1 alternate director to him/herself. So, I thought the easiest way was to put an autonumber in the Company-personID table and have a table (alternates) that had two fields, "alternate" and "director", both using that autonumber to link them. However, it appears as though I can't link the same primary key twice to two foreign keys of the same table.
I'm developing a simple sporting records db. I have a 'Competitor' table listing competitors as follows: CompetitorPK, Name, Division, Club. I have a 'Contest' table listing contests as follows: ContestPK, Competitor1_FK, Competitor2_FK, Winner_FK, Score etc. My question is have I modelled tables correctly i.e. CompetitorPK will appear in three columns of Contest table. How do I define this relationship? What alternative is there to what I have done.I intend to use forms to populate both tables (independantly obviously).
I am trying to model my database to create relationships between different tables in my database. During the process of doing so I ended up having one primary key in table A linked with to foreign keys in two different tables ( table B & table C) and both of those two table are junction tables to break out many to many between many other tables
Now for some reason!!! I feel that there is something wrong with my logic mapping and modeling of the relationships between tables due the fact of having one primary key linked to two foreign keys in two different tables :(
Is my intuition is right? should such case be considered as indicative of wrong modeling of relationships between tables in a single database And if so what is the disadvantages of that link (talking down the road) when the database if fully populated? :confused:
By the way I am new member and new to database, so please take it easy on me :o
I have a table for a multiple parents linked to a child table. I need to figure out a way to only allow 1 parent to be coded as primary, 1 as secondary, and then the rest as other... I thought about making Primary/Secondary/Other a primary key. But then I can only have 1 other. I would have to make a finite number of parents that could be entered and I want an infinite number.... My end goal is to have a report that only has a primary and second parent on it, but the rest of the parents still exist in the table...
Access 2010..One organization that we work with provides us with a block of numbers for each of the two types of contract products we order from them; we do order non-contract stuff from them also.The block of numbers are the same (i.e. 20000 to 30000 this year) for each of the two products. This means that each product can have the number 20000, for example. We call this the Tracking Number. If it is one of these products, we need to select the Contract Number.
For all other one off orders we have with them, we assign our own Tracking Number starting with 00001. This Tracking Number cannot duplicate unless it is one of the aforementioned two products.Both the Tracking Number and Contract Number are in the same table. The user selects the Contract Number from a form (connected to the Contract Number table that has all the details on the contract) and the Contract Number is populated in the same table that has the Tracking Number.Each order must have a Tracking Number (no null)..Not all orders need a Contract Number (null okay).The Tracking Number and Contract Number combination cannot duplicate.I tried setting the primary keys to more than one field in the table, but they cannot have null values.
If not... I have been working on Plan B.... an AfterUpdate on the form (either the form or a field... don't know yet) that looks at a query that only has results if there are duplicate values.
hi i need to create a table, i've figured out to make LastName the primary key. But im not so sure about the foreign key, and whether it is necessary to put it into the table in order for all my tables to relate? Sorry if this doesn't make much sense. Also, to clarify.. 3NF primary keys in one table cannot be used in another table?? thanks
I've got a table - "Products" - in my database, with a text field - "Info" - which contains info about products.
Within this field I would like to have footnotes. To do this, I think the best way to do it is by putting numbers inside the text at the location of where I want the footnote to refer to. These numbers will actually be foreign keys to a table called 'Footnotes'.
I can then program the forms and reports to show any numbers as superscripts or whatever.
(Of course, if the user will actually want to insert a number into the text field which is NOT a reference to a footnote, I will have to make a workaround e.g. by making access put a symbol in front of the number, so access will know the number is just part of the text (and I will program the form to not show the symbol in front of the number)).
Is it wrong to have foreign keys within a text field? I think if executed correctly, it should work perfectly.
I'm not new to access, and I understand normalization at pretty much all its levels, but right now I'm curious about a situation that I have just come across. The first time I've been in something like this, so I thought I would ask.
This is the setup.
I have employees. They are apart of a shift and a budget. Shifts and budgets are completely independent of each other.
The database needs to keep track of shifts and budgets over time. Therefore, 1 to many relationship to shift table and budget table.
But, the database also needs to keep track of attendance. And the user wants attendance tracked by Shift and Budget.
Shift and budget are completely independent of each other.
Currently, I have the relationships set up like this.
When a new attendance record needs to be added, both the key to the budget and shift are added to the attendance table. The key chosen is dependant onthe Employee chosen, and whether the budget and shift are the CURRENT budget and shift that the employee is apart of.
I thought of running a query showing budget and shift by date descending, so that the latest budget / shift would be displayed, and thus the most current (SUPPOSEDLY) But, if a user put in a different date, or screwed up on the date, then the incorrect shift and/or budget would be displayed.
Date stamping an entry was an option, but there needed to also be a user entered date as well, to specify WHEN a user began working in that specific budget / shift. Therefore two date entries would be required. Duplicate entries in most cases.
I therefore decided to go with a true/false yes/no checkbox. Where the current budget or shift would be checked, and all non current ones would be unchecked (false).
Currently, this is how the systems works. And it works well. But it is dependent on some form code I created to set the yes/no checkbox to true/false depending on the situation.
I DON"T like doing this. Am I missing a way to do this "correctly" where by Access would do this "automagically" instead of via my trick.
The ONLY issue really, is that when a new attendance incident occurs, the user needs to put in the incident to the approbriate shift / budget. And if the current shift / budget could automatically be displayed without user intervention (IE user has to pick the shift / budget from drop down box after looking up info etc etc) since the current information SHOULD be known.
I've never done a table setup where two foreign keys are the many side of the relationship in a single table.
It is currently working fine, and seems to do well, but I wanted to make sure with others who might have had this experience. And also, any "advice" / "cautions" for this kind of situation so I don't step into it deep and have to fix it later.
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.
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
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:
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?
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:)
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
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?
I have two tables tblPatients (pkUMRN) and tblAdmissions (pkAdmissionID, fkUMRNAdmission). pkUMRN is not auto-number, but is an 8-digit alphanumeric code unique to each tblPatients record. I have set up a one-to-many relationship between tblPatients_pkUMRN and tblAdmissions_fkUMRNAdmissions (each patient can have multiple admissions).
Is it possible to allow the entry of a new tblAdmissions_fkUMRNAdmissions to create a new tblPatients_pkUMRN? IE can you create a new primary key from a new foreign key?
Along a similar line, if the primary key already exists, how would you autofill a form with data from tblPatients when the tblAdmissions_fkUMRNAdmissions is entered in to the table?
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??
I've built a system with around 20 tables in it. All of these use the standard ID field offered by default by Access as the primary key. A friend with a background in database design and development for large corporates using Oracle has reviewed the database (he is going to do some VBA programming for me) and suggested that we use more appropriate primary keys based on data attributes.
He has read "somewhere" that there are problems with the standard ID fields and that occasionally the fields are renumbered/reindexed and that this can cause problems. There are a fair number of queries and some complex forms which will need to be updated for these changes but it would be a shame to go through all this work if it isn't really.
Should we use the standard Access IDs and is it worth a chunk of effort to change from where we are now?
Is it possible for the primary key of one table to act as the foreign key in another table for more than one columns? What I'm trying to do is create a table for a Committee which will have 1 student and 5 professors! So Can I import the faculty ID for each of the 5 faculty members?When I try creating the second relationship, access automatically creates a new Faculty table for the relationship!
Builder Subdivision Lot Number Lot Option Lot Materials Details
The [Lot Materials Details] table is populated by appending data from the [House Type Details] table tree as follows:
Builder House Type Elevation Options Per Elevation House Type Materials Details
The filtered Option Table in both branches determine which [House Type Materials Details] records get appended to the [Lot Materials Details] table.
The question is: Is there any advantage, other than simpler queries later on, to adding the primary key from the [House Type Materials Details] table to the [Lot Materials Details] table.
It’s redundant because the [Lot Options Table] contains the [Options Per Elevation] primary key.
