How i do a crud with a relationship between a user and services order? With the code, i can't add users in a team for service order. When cakebake, the controller TeamHasUsersController is created, but the form add don't have any field.
The crud has generated with cake bake.
In service_orders: change requester_users_id into user_id, the icon in front of the field will change to a red key (foreign key). Cake conventions need a foreignkey to be named [model]_id.
The name of table with associations should be "team_users".
Three database tables are required for a BelongsToMany association. In the example above we would need tables for articles, tags and articles_tags. The articles_tags table contains the data that links tags and articles together. The joining table is named after the two tables involved, separated with an underscore by convention. In its simplest form, this table consists of article_id and tag_id.
habtm relationship
Related
[user Database model][1]
https://www.linkedin.com/feed/update/urn:li:activity:6345250684744630272
here is my database design for user I want to add user_ following table in this scenario can anyone help me to build user_follower table scheme?
1- Each User has many other Users that followed him
2- Each User can follow many Users
So you have a many-to-many Unary relationship on User in your ER.
Now, to Mapping this data model to Tables: you can use a new table named: User_Followers and set 2 IDs of User as foreign key named source and target of following (and other attributes like date of follow and etc.)
you can find other mapping many-to-many Unary relationship (like Bit-Wise or Graph Data Models), but to your project, I offer as I mentioned.
Can someone tell me the easy way to explain the differentiation between an entity and a table in database?
Entity is a logical concept of relational database model. And table is used to express it, but there is a slight difference. Table expresses not only entities, but also relations.
For example, assume that you want to make a database of projects and employees of a company. Entity is a unit of information that has meanings by itself. In this case, there will be two entities - "Project" and "Employee". Each entity has its own attributes.
In relational DB model, there is another idea, 'relation'. If employees participate in several projects, then we can say that there is a relation with a name 'works_on'.
Sometimes, relation can have its own attribute. In this case, 'works_on' relation can have attribute 'start_date' and so on. And if this relation is M:N relation(Like this case: In project 1, there are 5 employees. Employee A works on two projects.), then you have to make an extra table to express this relation. (If you don't make an extra table when the relation is M:N, then you have to insert too many duplicated rows into both 'Project' and 'Employee' table.)
CREATE TABLE works_on(
employee,
project_id,
start_date
)
An entity resides in a table, it is a single set of information, i.e: if you have a database of employees, then an employee is an entity. A table is a group of fields with certain parameters.
Basically everything is stored in a table, entities goes into tables.
In a relational database the concept is the same. An entity is a table.
In OOP (Oriented Object Programming) there is a nice article in Oracle docs:
In general terms, entity objects encapsulate the business policy and
data for
the logical structure of the business, such as product lines,
departments, sales, and regions
business documents, such as invoices, change orders, and service
requests
physical items, such as warehouses, employees, and equipment
Another way of looking at it is that an entity object stores the
business logic and column information for a database table (or view,
synonym, or snapshot). An entity object caches data from a database
and provides an object-oriented representation of it.
Depending on how you want to work, you can create entity objects from
existing database tables (reverse generation) or define entity objects
and use them to create database tables (forward generation).
There is little difference between an entity and a table, but first we should define the concepts of “tuple” and “attribute”. I want to express those concepts with a table.
Here is an example of a table. As you can see it has some columns. Each column represents an attribute and each line represents a tuple(row). This is the employee table. In this example, the table is being used for representing an entity which is employee. However, if we create a new table named superior to specify the superiority relationship between those employees, it would be a table that represents a relation. In summary, we can use tables for representing both the entities and relations so entities and tables are not the same.
What is the right plural/singular table naming convention in CakePHP.
This:
posts
posts_pictures
posts_picture_captions <-- Not sure about this
Or this:
posts
posts_pictures
posts_pictures_captions <-- Not sure about this
I know CakePHP want the tables in alphabetical order but this should in this question ignored. Please only consider plural/singular table naming.
Cake Inflector Should do exactly what you are looking to do.
From the cakephp book:
Model class names are singular and CamelCased. Person, BigPerson, and
ReallyBigPerson are all examples of conventional model names.
Table names corresponding to CakePHP models are plural and
underscored. The underlying tables for the above mentioned models
would be people, big_people, and really_big_people, respectively.
You can use the utility library Inflector to check the singular/plural
of words. See the Inflector for more information.
Field names with two or more words are underscored: first_name.
Foreign keys in hasMany, belongsTo or hasOne relationships are
recognized by default as the (singular) name of the related table
followed by _id. So if a Baker hasMany Cake, the cakes table will
refer to the bakers table via a baker_id foreign key. For a table like
category_types whose name contains multiple words, the foreign key
would be category_type_id.
See http://book.cakephp.org/2.0/en/getting-started/cakephp-conventions.html#model-and-database-conventions
So at first, your "posts_pictures" table should be named "post_pictures".
As a result, neither of the two is correct. The correct name according to the cake naming conventions is "post_picture_captions".
Cake newb here.
I have two tables. Users and Events. An user can subscribe to Multiple events.
What is the best way to implement this?
Do I have to create another table and link them or is there any other better approach.
If I do create a new table, how do i link them in cake model?
As said by jQuery.PHP.Magento.com you should use HABTM relationship but the name of the third table should be events_users because the table names should be in alphabetical order.
From the doc:
Table names are in alphabetical order by convention. It is possible to
define a custom table name in association definition.
You should use HABTM relationship.
Reason
See users will subscribe to Multiple events and
One event have multiple users subscribed for.
So this is two way relationship. Therefore you need following tables
users : To store user's data,
events : To store user's data,
events_users : To store Which user joined Which event and Vice versa(Events with n number of users)
So users_events will have 2 fields user_id , event_id , both are foreign keys and here you dont need primary key in HABTM relationship.
I was wondering if this is possible to do with a has many through
contents orgs folders
id id id
name name title
link
join table - folder_elements
id
element_id
order
contents has many folders through folder_elements
orgs has many folders through folder_elements
So my question is, is it possible to use element_id to store the content.id or the org.id ?
Alex
What you're describing is a sort of HABTM (HasAndBelongsToMany) association. You could define the inter-model associations as you suggest, but there's a pretty significant design flaw: how would you account for a situation where the same ID is used for an orgs record and a contents record, and wish to associate them with the same folder record? It would be impossible to differentiate between the two in your joining table.
There are a number of ways to work around this, but they require more program logic or a more disorganised database schema that presents challenges in maintainability.
The more elegant, robust solution is to rationalise your database structure. If there's no pressing need to have One Join Table to Rule Them All, you could design your model associations like this:
Content hasMany ContentsFolder belongsTo Folder
Folder hasMany ContentsFolder belongsTo Content
Org hasMany OrgsFolder belongsTo Folder
Folder hasMany OrgsFolder belongsTo Org
This is the internal structure of a HABTM association defined explicitly so you can define fields in the joining table. Your contents and folders tables would remain the same, but your two joining tables would look like:
contents_folders
-> id
-> content_id
-> order
orgs_folders
-> id
-> org_id
-> order
Unfortunately, yes, this would require defining five models instead of three, but such are the limitations of CakePHP's object-relational modelling.