Redundant Foreign Keys?
Jul 8, 2005
More on the lot materials management program.
I have a series of related table:
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.
Any thoughts?
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Aug 25, 2006
Hi,
While designing a database, I came up with 3 different foreign keys in one table. I am afraid this is not right!
Is it possible to have this number of FK in one table or does that suggest a design flaw?
Any help will be very much appreciated.
B
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Apr 20, 2006
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.
Employee (1) ---(Many) Budget (1)------(Many) Attendance
Employee (1) ---(Many) Shift (1)--------(Many) Attendance
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.
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Sep 25, 2006
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
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Aug 5, 2007
Wow, I've found some good stuff here already... Thanks.
PROBLEM:
I have a table(we'll call it shipping) that has two columns FK'ed to another table (locations). My problem is I have no idea how to pull the information from the locations table into the shipping table.
DESCRIPTION:
My shipping table has a source and a destination column. Now, I have a fixed location list that applies to both columns and I'd like to avoid having a source tbl and a destination tbl... I'm an Access Neophyte to say the least (for now at least) but I have managed to put together a querie that pulls out most of the information that I need (name, phone number, yadda, yadda, yadda) but I can't seem to correctly link the FK's for the sources to the locations table as well as the FK's for the destinations to the locations table. When I run my querie I get an error or my Source(destination) column will display the correct information but the Destination(source) column will display ALL of the locations in the location table. Here's what I mean:
Source destination
detroit toledo
detroit cleveland
detroit San Diego
detroit London
detroit Paris
detroit detroit
Paris toledo
Paris cleveland
Paris San Diego
Paris London
Paris Paris
Paris detroit
.
.
.
The first and second source was detroit and Paris but the Destinations list all of the locations I have in the table.
How can I link two FK's in one table to another table in a querie?
Thanks.
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Oct 5, 2015
Can a table have two foreign keys?
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Jun 14, 2007
Hi,
I have to create a database for work and for my sins I have to use Access. We are running 2007 but I'm having some difficulty in creating foreign keys in my linking table.
I've searched their help guide and looked on the net but I can't seem to see how I physically create foreign keys.
My structure looks like this:
Customer
CustID (autonumber)
Cust Name
Cust contact
Cust email
cust version
no of users
other info
Modules
ModID (autonumber)
Module name
licensed module? (tick box)
MiscSoftware
MiscID (autonumber)
Software
Installed on live
CustMod
ID
CustID
ModID
MiscID
Thanks
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May 30, 2012
I want to create a combo box filter - easy enough usually
However - the field I want to use is a foreign key field which, while it displays a meaninful description - it stores the id rather than the text
I want to create a combobox filter, but when I do all I see is the id's - which are meaningless to the user.
Is there a way to get these foreign key filters to display a meaningful text description??
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Sep 22, 2007
Hi there,
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
Many thanks
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Aug 28, 2013
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.
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Jul 10, 2014
I have what I think is a normalised database that uses foreign keys quite a bit.
For example if I had a 'contracts' table which refers to 'clients', then there would be a tblClients, where each client has a primary key. The tblContracts would then refer to the relevant client via that clients FK only which would be linked to the client's PK in tblClients via a one-to-many relationship.
If I need any user for any purpose to see contract related information that makes sense to a human being, I simply construct a query with the necessary relationships that will show client information alongside contract information by substituting tblContracts' client FK with required information from tblClients via the appropriate relationships.
I think that is reasonably basic stuff (hopefully correct practice!)
But what about when I come to import a block of new data that needs to go into tblContracts? I'm not going to be given a list of client keys (obviously) I'm going to given their real names.
MS Access has (in theory) all the information it needs (via the relationships) to substitute client IDs (keys) for their real names and thus slot these IDs into tblContracts with the new data as appropriate, but how do I make it do this? (I know it could kick out errors if there are any duplicate client names, but let's put that to one side for a moment).
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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.
[URL]
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May 4, 2006
I need some help creating a simple datebase to store my documents and other knowledge objects. There are two types of
knowledge objects I need to store: Documents and Questions/Answers. For this reason I have created three tables: Index,
Question, and Document.
The problems I am encountering is that the ID field in the Index Table is the Primary and relates to the ID field in the
other two tables. So basically when I am entering information it can either be a question or document. I want to create a
for so that when its a question that I am entering it records the information in the question table and when its a document
I am entering it records the information in the document table.
I'm a beginner at using access and don't know VB or SQL. Any help would be appreciated.
Table Structure
Index Table
ID (Primary Key)
Link
Type
Source
Reference
Question Table
ID (Foreign Key)
Question
Answer
Document Table
ID (Foreign Key)
Title
Summary
Notes
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Mar 26, 2013
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).
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Jan 25, 2015
I'm trying to understand how data is passed using foreign keys.
I'm using Allen Browne's 'Don't use Yes/No fields to store preferences' at: [URL] ....
I've also downloaded his sample DB, RelationBasics, to use as a guide.
Attached is my version of the Student / Sport DB as described on the webpage.
I use 2010 at home (saved as 2003 version) and 2003 at work (JPNSE OS). Both result in the same thing.
The problem I'm having is I cannot get the actual sports to display in the combo-box, only the Sport_ID number.
I've tried building both forms with and without actual data in the TBL_Student & TBL_Sports tables, but no mater what the result is the same.
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Jan 22, 2013
I am using access 2007
i have a materialsUsed tbl that list all the materials used in a job and the quantity of each.
(ID
Material Code
Quantity
Unit of Measure)
I also have 2 look-up tables - 1 for the material codes and 1 for the units of measure
I have another table, priceperunitofMeasure
id
material Code (FK to material lookup tbl)
Unit of Measure (FK to unit of measure tbl)
Price
In my form Users will select material code from combo box - enter the quantity, and select a unit of measure from a combo box.
For example: they could enter the following :
Paint 2 gallons
Paint 3 tubes
Paint 1 pint
How do I lookup the price per unit of measure for each of these records in the price per unit of meassure table? The price per unit of measure table has 2 foreign keys.
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Sep 14, 2004
Each pay period, I must enter data for each employee that worked an extra shift. The table is simple:
Name
Period Starting
Period Ending
Number of Extra Shifts Worked
Is there a way to bulid a form that will keep the dates I type in the period starting and ending fields until I change them?
To clarify, I have 17 employees who worked extra shifts, and I don't want to have to type in the Period starting and ending dates for EVERY record. Thanks in advance for any help. I really appreciate it.
KellyJo
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Jun 30, 2006
I wasn't sure where to post this, so here goes:
Very basically, I have two related tables that I'm working with.
TABLE #1:
tbl_MAIN
FIELDS:
REC_ID (Autonumber) Primary Key [PK]
EMP_NAME
EMP_ADDRESS
DEPT_ID (Foreigh Key [FK] from the tbl_DEPT table...)
ETC...
TABLE #2:
tbl_DEPARTMENTS
FIELDS:
REC_ID (Autonumber) Primary Key [PK]
DEPT_NAME(Text)
ECT...
Now, I'd like to create a form that can enter information on the employee, including the department that they're a part of. I'd like to avoid having duplicate departments in tbl_DEPARTMENTS, but I want new department entries to be created if an employee from a new department is entered into the form. I'd like employees from a previously existing department to get associated with the department entry already in tbl_DEPARTMENTS. Is this possible? What's the best way to do this? I've tried every way I can think of, but I can't get this to work.
Thanks for any advice you can give me.
- Corey
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May 21, 2007
Dear All,
I have a table with several fields.
Concentrating only on few fields I'd like to sort out redundant information (unnecessary records).
(It is similar to using Ecxel: Data>Filter>Advanced filter>Unique records only)
So, I'd like to ask for your help how can I reduce my table to unique records.
thx
Csaba
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Jun 13, 2007
Hi All
Can anyone help me with this problem?
I have an 11 million row table that lists relationships between pairs of people. There are several columns, but the relevant ones for my problem are
personA, personB, a-b_strength, b-a_strength.
because of the size of the table i'm having all sorts of problems, and i could actually cut out half of the rows, because for every row listing eg
dave, steve, 4, 5
there's another row listing the same information, but flipped round, ie
steve, dave, 5, 4
I'm sure there must be an efficient way to delete, using a query or otherwise, one of each of these pairs (it doesn't matter which). I have another column (id) that simply has a unique number for every row, ie 1,2,3->11 million, so i was thinking of something like
delete
from table t1
where exists
(select *
from table t2
where t1.personA = t2.personB
and t1.personB = t2.personA
and t1.id < t2.id)
So, this should delete every row that has a mirror version earlier in the list.(i think)
What i'm worried about though, is performance: is this going to make a new temporary table for the nested select for each new row in the outer statement? I already created a table that listed the count of friends for each unique person with a make table query, and that took 12 hours to complete. I don't mind another 12 hour query, but not a 144 hour query!
Any advice welcome - thanks! (Sorry for the longwinded post)
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May 13, 2013
I'm doing up a database of hazardous chemicals, based on publicly available information from various agencies. Each chemical has a name and a number, and has different hazards associated to it. The hazards are grouped into classes, and for each class the hazard is further broken down into categories. Hence for an explosive hazard (the class) I could have categories 1, 2 and 3 based on severity. For each iteration of the hazard class and category (for example explosive hazard category 1), there is a non-unique hazard statement. Another complication is that there is a qualitative element in the classification system, and hence agencies from different countries could classify the same chemical differently. This should be captured into the database as well. Thus for every chemical, I will have to enter the Japanese classification, the EU classification, etc.
I've managed to set up what I think is a correct relationship, based on my understanding of databases. However when I generate the report, fields such as the chemical name and ID are repeated for each hazard. I would like to merge these redundant entries, so the chemical name, I.D., and any other repeated fields appear only once. In essence, I'm trying to make it such that there is only one entry for each chemical+I.D/country, with multiple hazard subentries, rather than having multiple, seemingly duplicate entries.
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Jan 2, 2007
Hello,
I am using the access program to create a mailer. The fields are really basic... Name and address....
Many of the fields are going to be identical. City, state, zip code for instance.
The way we had it set up on our first try was to create the data base with all of the fields empty and to input everything over and over. I imagine there has to be a way to set it up so you only have to enter "San Diego" or "CA" once and then simply do manual entry of the names and street address.
Any help getting me started would be well eppreciated.
Thanks
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Oct 15, 2007
I work with an Access database with about 20 tables that requires considerable manual data entry. Although it is time consuming, the bigger problem is the keypunching errors that inevitably occur. A colleague of mine said that some databases can be set up so that two (or more) individuals can enter the same data into the database (basically creating two separate, temporary databases). At the conclusion of this double data entry, the two databases can be compared to see where they differ so that corrections can be made...the logic being that it's extremely unlikely two people entering the same data independently will make the same keypunching error in the same field.
Just wondering if Access has this capability, or if a reasonable facsimile of this approach exists.
Thanks!
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Jul 28, 2014
I'm working on a scheduling system for my fathers company that automates some redundant tasks. Most importantly the system manages the order of processes on different parts (ie, part "tubes" may be cut, then drilled, then welded, then shipped).
I'm trying to create a form that allows for the editing and viewing of all the parts and the processes for each part for a specific work Order. Ideally the information that applies to all the parts (Work order Number, due date etc) would appear at the top of the form with all of the processes to appear beneath (Separated into groups - all the parts to be welded shown together). My problem with using sub forms for this was that I need all the records to be shown without scrolling. Is there a way to dynamically change the size of each Subform to match the required size, or is there a better feature to use?
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Apr 3, 2008
Ive got problem with defining foreign key
i explain what table ive and what i want
between my Student ,Session there is many to many relation that student session connect them together
student: Format student session: Format
Student ID Autonumber Student ID Autonumber
student name Session ID Autonumber
student address
student dob.....
....
Session: format
Session ID Autonumber
dance days
dance time
no of student
the student id is primery key and session id is primery key ,student session is compound key of this 2 but it wont work it keep saying u can only have one auto number in one table #
what should i do ?
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Mar 19, 2007
Hi all,
my question is what is a foreign key and how is it used ?
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