relationships

问题 i want to access to data in the function of the controller using relationships on Laravel. I will explain first my code: I have 3 tables, projects, client and client_project. At this moment, client_project don't have any relationship, i just add it manually. Now i want to use relationships on laravel, but it's a bit confusing (for me at least). I think it's not too much important the code of projects and clients table, just have id like primary key, and some fields more. My migration of

问题 I am bit confused on making a good relational database. I am using phpmyAdmin to create a database. I have the following four tables. Don't worry about that fact place and price are optional they just are. Person (Mandatory) Item (Mandatory) Place (Optional) Price (Optional) Item is the main table. It will always have person linked. * I know you do joins in mysql for the tables. If I want to link the tables together I could use composite keys (using the ids from each table), however is this

问题 I am new to Core Data and objective-c. I am working on a project where I am taking JSON data from a web service and syncing it with core data. I successfully followed this tutorial and am able to get the JSON into core data without any problem. Where I am having trouble is updating the NSSet associated with a to-many relationship. So far I can get it to update but in doing so its creating duplicate entries in the set. For example, I tried using the Xcode generated access method in my custom

问题 Say I have three tables in a declarative fashion, Parent , Child , and Pet , in such way that Parent has a many-to-many relationship with both Child and Pet Child has a one-to-many relationship with Pet The code for them is (using Flask-SQLAlchemy, although I believe the solution lives in the realm of SQLAlchemy rather than in Flask). class Parent(db.Model): __tablename__ = 'parents' id = db.Column(db.Integer, primary_key=True) name = db.Column(db.String(64)) # many to many relationship

问题 Here's my situation. I am building a database to track relationships between people and households. Typically, everything is tied to a "head of household". I am trying to avoid this as it creates problems when people move (i.e. brother finally gets a job and moves out) or families break up (i.e. dad and mom get divorced, household is now split into two, some kids stay with mom, some with dad). It is a huge challenge to figure out how to cascade the data when the model is based on HOH. My

问题 i have a project table which has a image_id field and a newsimage_id field. Both are linked to the image table. But InnoDB doesn't allow me to set a foreign key for both fields to the same column ( id ). Is there a way I can do this or is it not possible? I'm using MySQL through MAMP. Thanks in advance!! 回答1: Here's how I did it (MySQL 5.0.45): ALTER TABLE `job_dependency` ADD FOREIGN KEY (`job`) REFERENCES `job` (`id`), ADD FOREIGN KEY (`dependency`) REFERENCES `job` (`id`); There are

问题 I'm trying to implement this project: http://img7.imagebanana.com/img/cnb46ti2/relationships.png I want to let view the skills of an employee on the employee's show page An employee has a position, and every position has skills which an employee of this position needs to know so if I understand right, positions and skills have an n:m relationship, and they need a join table for a has_many_and_belongs_to_many relationship. Because a position includes many skills and every skill belongs to many

问题 Fundamental misunderstanding of model in Eloquent (Outside of Laravel) My previous question that ceejayoz helped point me in the right direction for, but that has led me to what is basically a new question. I'm working on a simple chemical tracking database and have it structured with a chemicals table which tracks most of the info but I have a few fields that started out as Enums but I realized that would not work for. There are now separate tables for company, room, and location. All of

问题 I know I had already asked this question, but I have misunderstandings yet. My previous question: Liferay and relationships in it In two words: I have a portlet, which can add/update/delete books and add authors. Moreover, you can choose existing authors when you try to add book. http://i.stack.imgur.com/vzUjn.png And now I need to show how many books were written by each author in "author" table. My service.xml: <entity name="Book" local-service="true" remote-service="true" cache-enabled=

问题 I think, this problem is of more advanced SQL category (MySQL in this case): I have two tables ( TABLE_FRUIT , TABLE_ORIGIN - just example names) which have columns that can be joined ( fruit_name ). Consider the following diagram: TABLE_FRUIT fruit_id|fruit_name |variety --------|---------------------- 1|Orange |sweet 2|Orange |large 3|Lemon |wild 4|Apple |red 5|Apple |yellow 6|Pear |early etc... TABLE_ORIGIN fuit_id |fruit_name|Origin ---------|----------|-------- 1|Apple | Italy 2|Pear |