one-to-many, relationships | FileMaker Community
Understanding and creating many-to-many relationships in FileMaker Pro An example of a one-to-many relationship is a single order has many items on that. SIDE TIP: One-to-One relationships are rarely utilized in FileMaker Pro. They are so It joins the two outer tables with two one-to-many relationships. We'll call. One method of having a many to many relationship in FileMaker is to use a join FileMaker Pro is the registered trademark of FileMaker Inc.
FileMaker has a good overview of the different types of relationships you might create when building a database system in its help section. I wanted to illustrate it better for a client, this is my attempt. Overview One-to-Many Relationships are the standard way of building a relational database. Sometimes a developer comes up against situations where they need something more complicated. Think of instances where you might need Many-to-Many Relationships. In the situation I am working on, we needed a way for multiple Customers to be linked to a single Form.
The form was a waiver and customers were signing up for themselves and their children at the same time on the same waiver form. We needed a way to link the waivers not just to the parent, but also to the children. One-to-Many Relationship Standard database relationships are created by linking ID numbers between data tables.
These fields are referred to as key fields. The image above is an example of a regular database relationship—one record the Customer can be linked to multiple Form records. In this example a Customer record could be continuously updated with a more current form — One Customer to Many Forms.
If you are going to be dealing with a lot of corporate sales and different people at each company, a company table makes sense. If most of your sales are to individuals, a company table just gets in the way and makes it more difficult to enter orders.
The rest of the possible entities are for you to determine for your unique solution. The examples covered so far are exhaustive enough to help you understand the process of turning entities into tables. You can see why I like to skip this step in the process and go right to the ERD. I have been creating database solutions for over two decades and I naturally think in terms of relational design.
The first example is a solution tracking movies and actors. Ask yourself from the perspective of a single record in a table, whether the associated table can relate to just one one or more than one record. Then reverse the perspective and ask the same question. In this case, one actor can be in many movies and one movie can have many actors. The answers to these two questions tell you that you have a many-to-many relationship.
A many-to-many relationship is indicated by crows feet on either side of the relationship line. A one-to-many or many-to-one relationship is indicated by crows feet on only one side of the relationship line. A one-to-one relationship is rarely used in FileMaker but can be indicated with a straight line and no crows feet.
FileMaker Many To Many Relationship Example — thePRACTICALba
One artist can have many paintings and one painting can have one and only one artist. Is this always true? What if you have a mural then the ERD would look like the following. Not every artist database is the same. I have seen amateur developers assume so many times that I expect it is going to happen. One time at MacWorld when I was giving a presentation, someone commented that they wished their developer had been more inquisitive.
If the developer had only asked, he would have realized the school he was designing a database for was a grade school and not a high school.
Remember, this is not an isolated case. Ask even if you think you know the answer. I am often surprised at the answers I get and often prevent structural issues and a lot less headaches. One-to-One relationships are rarely utilized in FileMaker Pro. They are so uncommon, it is difficult to even come up with a good example.
- Join Tables in FileMaker Pro
- one-to-many, relationships
- One-to-many relationships
While one-to-one relationships are common in other database products, you are better off just creating fields in FileMaker. FileMaker design choices are often different than other databases. In this case, blank fields do not cause any overhead to the system as with other database applications. In fact, just the opposite occurs in FileMaker where one-to-one relationships can make a solution overly complex. There are endless numbers of simple ERD examples. The more examples you see, the better you will become at recognizing the necessary relationship type.
Scroll through the examples below and verify the relationship type. The most common relationship type has been drawn. As practice, ask yourself if there are any exceptions to the common relationship type assigned. The ERD for our invoicing solution can be expressed as a simple or complex diagram. For purposes of training, I am going to include only the most important tables at this point. During a normal development cycle, all or almost all of the tables would be identified to ensure a healthy structure.
Instead, we will add tables onto the project as needed to keep the process as straightforward as possible. A complete ERD at this point would just be overwhelming and leave too many questions unanswered.
Creating a One-to-Many Relationship in FileMaker
Adding every single table at this point will just muddy the waters and complicate the learning process. The following ERD diagram shows the most important pieces of the equation. The first relationship you need to notice is the many-to-many.
Multi-keys will be covered in other articles on this site in order to stay on task. For a structurally sound relationship that supports ad hoc reporting, a join table is required.
A join table is just as it sounds. It joins the two outer tables with two one-to-many relationships. Each time a product is sold, a record is created in the line items table along with a unique identifier from the invoice and the product records. The identifier allows the invoices and products table to both see the same line item record, thus, joining the two tables together.
Databases are designed to handle lots of records.
Key Fields While key fields are not really part of the requirements document, I wish to prepare you for their inevitable use. Since tables and relationships are being discussed, it seems natural to discuss them now.
Each table should have a primary key. A primary key that uniquely identifies each record in a table. Primary keys are used in many ways but in terms of relationships, it is the value that keeps records from two different tables connected in a relationship. In the example of customers and invoices, the primary key identifying a customer is stored in a foreign key in the invoices table. Think of key fields in the same way you would think of keys to a household. Only one key can gain entry to the front door but duplicates can be made and handed out to anyone who needs to gain access.
The key hole is analogous to the primary key and the duplicates of the keys are the foreign keys. A record is created in the invoicing table each time a customer purchases products. Each invoice is associated with a customer by recording the primary key value from customers in the foreign key field in the invoices table. In fact, there are many ways to populate a foreign key as will be discovered in other articles on this site.
Primary key fields are typically assigned as auto-enter serial number values. By divorcing the connections between tables from data entry and using a value generated by FileMaker, relationships are safe from any changes to data. It certainly does uniquely identify an individual but what if the data entry person types it incorrectly. What happens if child records are related and six months later the data entry error is corrected. What happens to the related records?
They are orphaned since the foreign key values are not automatically updated. Serial numbers are not the only types of unique identifiers in FileMaker, just the most common. There is an internal identifier called a Record ID. This internal number is created automatically without any interaction from the developer.
It was first revealed using the Get RecordID calculation function for use in web deployment. What happens if you need to import data from one copy of your solution to another? The Record ID might not be the same and you have no way of changing it. Serial numbers can be manipulated in many ways, giving them flexibility.
While serial numbers avoid duplication by producing sequential numbers, UUID is a random value that is guaranteed to be unique. UUID was introduced in FileMaker to make it easier to create distributed systems where users have no internet access. Distributed systems synchronize remote users data with a centralized server. Without UUID, unique identifiers would be be a nightmare to produce.
Unless you have remote users that cannot get cellular or WIFI access consistently, save yourself the hassle of synchronization. It is far easier to use serial numbers and live connections to a database solution.
For example, UUID cannot be identified outside the context of the table while serial numbers can easily be preceded with letters to help identify the table from which it was spawned. Scrubbing Once you have completed your ERD, you need to test it against your requirements document.
This process is called scrubbing. The goal of scrubbing is to guarantee your ERD structure will support all the items outlined in your requirements document.
It is common to change your ERD dozens of times during this process. The goal is a structural design that will support the entire feature set including interface, reporting and future development. So, break out your number two pencil and a lot of paper, this process is going to take a long time.
It will be time well spent, especially for complex solutions of ten tables or more. The process is fairly simple. All you have to do is validate whether the items in your requirements document will work within the structure of your ERD. This can be done by creating a sample database and actually testing the feature or by simply running it through your head. In the beginning of your career, you may need to build more sample databases. How many times you scrub your ERD depends on the complexity of the project.
A rule of thumb to know when you are done scrubbing is when your ERD stops changing. When bugs continually decline over a period of time, the project is close to complete. Any flaws at this point will most likely be easy to correct in an update. These are fancy words that describe sound relational database design. FileMaker naturally prevents some relational mistakes and others must be learned.
It is not vital to memorize these terms unless you want to impress your friends. Rather, I offer them here for you to imbibe their meaning, not memorize their definition. I can never remember which form is which off the top of my head but I can design a relationally sound solution. Just understand the purpose of these forms and why they are important to relational design. Normalization is the process of efficiently organizing data in a database.
The idea is to divide large tables into smaller tables in order to reduce redundancy and duplicate data. This reduces the size of the database, increases efficiency and allows for easier updating of data across multiple record or tables. First normal form governs the shape of a record and warns against storing duplicative data in the same record.
Some designers like to describe it as atomic values that cannot be divided. For example, you might be tempted to enter all the phone numbers for a single contact into a single field separated by returns or into multiple fields. Instead, you could create a child table to store phone numbers. Reducing records down to their most granular level is the key to good relational design. The reason for these precautions is to allow for ad hoc reporting. If you store the extracurricular activities for contacts using a field formatted as a check box, which stores the data as a return-separated list, it will be difficult to report on how many people like cooking or watching movies.
Reporting in any database relies on organizing records. It is difficult to split up a record into different parts of a report. However, there are always exceptions to these rules. For instance, it is unlikely you will ever produce a report counting the number of phone numbers so you could consider making separate work phone, home phone and mobile phone fields in the customers table.
Exceptions to relational rules are fine as long as you know the consequences. Second normal form reduces redundant data by transferring it to another table. The classic example is city, state and postal codes in a contact manager table. By placing the data in a separate table, it is only stored once in the postal codes table but referred to many times in the contact table. It also makes it easier to enter the data. Just select the primary key associated with the postal code you want and the city, state and postal code automatically appear.
In addition, if the name of a city changes, just change the entry in the postal codes table and it will be updated in every contact record. In addition, you may not want to require users to select a primary key and opt to break the rules by using the postal code as the primary key so users can simply type in the postal code and the city and state are linked.
Relational design is not just about following the rules, it is about making educated choices. Third normal form dictates there be no transitive dependencies. It is in violation when one non-key field is a fact about another non-key field. For example, if you have a table storing employees along with their department and department location, this violates normal form because the location is a fact about the department in addition to being a fact about the employee.