I have tried to figure out what the difference in functionality would be between 1 and 2. In the latter I have just created a series of relations between the last two tables (but that structure could be used throughout the whole DB instead of hanging it together with one relation between tables as is the case for the rest of the DB in this picture).
So there can be three different situations with this table structure:
- linking all tables together via multiple relations
- linking all tables together via a single relation
- a combination of both, such as in the images.
Why would someone choose one versus the other? "Which is better in what situation?"
I've been fiddling about for a while now, but in a structure such as this it doesn't seem to make a difference. Or maybe there are differences in use/design, but on a level that I have not explored yet.
Could anyone explain this to me a bit? I have multiple books, all of which handle basic relations but I have not yet seen an explanation for this question. I think understanding the whole relationship topic is critical to be able to see other pieces of the puzzle fall into place later on. And as of yet, this is really fuzzy to me.
I was hoping you guys would have a recommendation. Do you know of a book or web site that offers workbook examples to help practice learning how to understand existing databases?
My biggest problem with databases has never been designing them but learning how to follow someone else's work. Some place to practice on this deficiency of mine would be great. Any thoughts?
Omits records that contain duplicate data in the selected fields. To be included in the results of the query, the values for each field listed in the SELECT statement must be unique. For example, several employees listed in an Employees table may have the same last name. If two records contain Smith in the LastName field, the following SQL statement returns only one record that contains Smith: SELECT DISTINCT LastName FROM Employees;
If you omit DISTINCT, this query returns both Smith records.
If the SELECT clause contains more than one field, the combination of values from all fields must be unique for a given record to be included in the results.
The output of a query that uses DISTINCT is not updatable and does not reflect subsequent changes made by other users.
So, from what I understand of this, if any of the fields in the record (or row, whatever) repeat then it is not displayed. Correct me if I am wrong.
The problem is that when I try and use it in my DB it return all the fields regardless of the Distict clause, unless I am only querying one field, which is next to useless.
For example when I make a test table that has repeating words in one field, with a unique ID for each one, the distinct clause works when I display the words field alone and not when I display the ID field as well.
Can anyone explain what is happening or what I am doing wrong?
I have to create reports from an Access database used in a commercial application. The backend uses Access but the front end does not.
The vendor does not document the data or provide any support for that. The database has over one hundred tables and thousands of fields.
I'm thinking I'll create small transactions in the application and then study the database to see what has changed. But this seems overwhelming considering how many tables and fields there are. So I'm looking for advice on how to approach this.
Hello i am a college student and i was just getting on with my database assignment. i don't want any one to do it for me i just want someone to point me in the right direction. i am making a basic Encyclopedia on planets for my project. i have made one form which i want all my other forms to look like. this form is getting its information out of queries. this form is opened when i click a picture of the planet. so i was wondering if it was possible if i could link all the picture up to the one form but each picture opens a different set of data with in this form. i have already thought of just copying the forms and changing the control source. just wondering if there is a different way of doing it.
ok, let me please ask this question regarding a payment relationship in my database
it will be paid in four ways, cash, creditcard, cheque, paypal
each of these payment types will have their own features..
eg creditcard (name on card, card number)
cheque (cheque date, date cleared)
paypal (username...YOU GET THE PICTURE
so is this below way a good way to store these details, or can i do it with 4 less tables..
http://bb.1asphost.com/antonyx6/untitled2.jpg
if this way is correct, i dont see how each id will be entered.. eg if i enter some cheque details.. will that lead the chequeid to be linked to the paymentid, and the paymentid to the bookingid, and the bookingid to the booking details etc
My problem is displaying data in many-to-many relationships.
There are three main tables: tblShops, tblOwners and tblMarketingEvents.
These are linked through two junction tables creating two many-to-many relationships:
1) Each Shop may have more than one Owner and each Owner may have more than one Shop. 2) Each Marketing Event may reach more than one Owner and each Owner may be reached by more than one Event.
Now I want to display for each Marketing Event:
1) the data of that event, (tblMarketingEvents) 2) plus the owners reached in that event, (tblOwners) 3) plus all the shops owned by the owners reached in that event. (tblShops)
Preferably, I want to display more than one record at a time without repeating any information.
Is there a way to display the data like this?
I tried a query: it gives the right data but does not display it as I need. It repeats the data from tblMarketingEvents and tblOwners for each shop.
I tried a form with subform: it can only display one record at a time and is hard to work with (printing etc)
I tried a report with grouping levels based on the query: Again, right information, wrong display. I need to group according to the records of the MarketingEvents table and not just according to a single field.
I'm trying to create multiple relationships between the same two tables, but I run into problems every time I try. I'm using Access 2007.
Specifics: I have a table with information on meetings and there are two hosts. So I have fields Host 1 and Host 2. I have a second table that lists possible hosts and their personal information. I have a relationship between table 1 "Host 1" and the Host in table 2; I cannot create another working relationship between table 1 "Host 2" and the Host in table 2.
how I can get that to work? With just the one relationship, I can go to table 2 of the hosts, click on their name, and see all their meetings.But if I add another relationship, it takes out all of the information. I've been working on this for over an hour,
how to export Access' many-to-many relationships in excel.
My database is a Project portfolio management tool. One project has many different fields, some of which can only be single values (one-to-one, easy to export to excel) and many others are multiple values fields, built as many-to-many relations (through junction tables).
One usage that was not specified at database creation time was the ability to export the portfolio to excel, so non-access-savvy users can browse, filter, sort and play with the portfolio however they want.
If I build a report, it will contain as many sub-reports as there are junction tables, rendering it un-exportable to excel. A Form would have to be continuous, barring the use of sub-forms for the m2m relations.
Building a query will generate many lines per project (as many as the most populous multiple field), making the excel sheet nearly unusable (in my users opinion, and here, the client's the king).
The best route I have been exploring so far involves "transforming" the multiple fields, so a the different "rows" become additional "columns".
Hi all. I really need help with this. Does anyone see a problem with my relationships , i have attached a copy. Any help will be greatly appreciated ClaireB
I am new to database design and curious about relationships. In a hypothetical situation, if I have four tables: tblProducts, tblOrders, tblEmployees, and tblCustomers, how could the relationship be set up?
The Products are stored to keep track of the quantity on hand and the employees will also need to be tracked as to how many products they sell. Customers are recorded and Orders wrap up all three tables with the fields: OrderID, ProductID, EmployeeID, and CustomerID.
Would it make sense to say that many products can be bought by many customers and/or many employees can place many orders.
I've selected a number of tables to the relationship window. When I drag the primary key on one table to the corresponding foreign key on another table, the link created is one-to-one. I want one-to-many. Why did it create one-to-one? How do I change this to one-to-many?
Hi all. I am new to the use of access and have been told that I need to create a one-to-many relationship to be able to have several records from a drop down list saved to one unique number (my primary key).
Is this correct and if so how do I do this? If it is not correct what is the best way to do what I require?
I have created two tables which are linked with a one-to-many relationship
Using a form the user enters a date. Then in VB I add a value to the date and store this in the second table.
I have simplified this to try to find out what was going wrong and found that when the database adds a value to the second table which only has two fields it first of all adds it to the begining of the record set and the id field does not update to that of the first table where the relationship is joined.
Do I just captutre the value of the id field and add this to the recordset. How to I get the database to look foir the end of record set before I appent the new generated record.
I have looked for this on the help section; however, it does not seem to be covered. How would you change a one-to-many relationship to one-to-one? Access seems to automatically guess that the many side is where the foreign key.
Can it be changed from Access or is entirely on how you design your tables?
Hi !! I am doing a school project on a school database. In my DB I have a table with all students records (eg. Student ID, Name, Surname, DOB, class etc) and I have another table where the student fees payment slips will be printed. The fee table will only have the ID, name, surname and class fields and fee will be input for every student for every term.
I want the fee table to get all the info except the fee from the first table automatically when I give a student ID.
I have created a one to many with only Student ID fields linked, NOTHING.
Then I tried to link many fields on each side (eg Name to Name, Surname to Surname etc) but I got a msg "No unique index found for the referenced field in the primary table"
would having a db with several tables and NOT setting any relationships up in the relationships window affect the db in any way?
i have such a db, which originally had all the relationships set etc. however, as i encountered errors and had to replace tables and delete entries, i must have at some point deleted all the relationships.
i just relaised that the db now has no relatioships set up (all the primary keys are still in the tables) so i'm wondering if this matters?
If I have a table "tblContinents" with just two fields ContinentID and Continent and I have another table called "tblCountries" with three fields CountryID, Country and Continent.
After reading several articles, i decided not to make the Continent field in the tblCountries as a lookup field but rather I will do that at form level via a combo box. In such situation, since i am not creating a lookup field at table level, do you think that it is necessary to create the relationship between the two tables in the "relationship window", or shall i just leave it as it is, and if the need arises i will create such "relationships" in queries?
hi, im new here and i dont really know much about databases with access. im currently doing an assignment at school requiring me to do a entity relationship diagram for all my tables, which i do not know how to do. Can anyone please assist me asap? thank you very much in advance
below is the link where i uploaded it because it was too big to be uploaded onto this post. :)
I want the one-to-many relationship to be based on my own generated quote reference rather than the PK/FK.
My quote reference looks something like this IN123/10
Does the character '/' cause a problem with creating the relationship as I get the error message "No unique index found" even though I know that they exist?
When I view the relationships window, not one of the relationship connector lines (whatever the technical term is) do not show up! I click view all relationships, view direct relationships. I restarted my computer, restarted Access. Nothing!
I know I have relationships because when I am table design view I try to change something that I know has a relationship and it doesn't let me because it says I have a relationship.
Here is what I have. The database is made up of three tables (see below and see attachment). I have it set as one event to many ethnicity's and many personnel with the event ID as the PK in all three. Did I do this correctly? I thought I did and I had a form with each one of these running correclty but now it is not working.
tblEvent EventID(PK)
tbleventEthnicity EventID (FK)
tblPersonnel EventID(FK)
See attachment for the other fields.
Can someone just check to see if I set this up correctly or what I should do differently?
