relationship

问题 Let's say I have the following relation: Reference(slide_id, group_id) where reference is the association of a slide and a group. One slide can be used in many references (with a different group): primary key is slide_id + group_id , which must be unique. I want to have all the references deleted when either of the pointed group or slide are deleted. Which I do by adding a cascade in the backref of the relationship: # definition of Reference model slide = db.relationship( Slide, backref=db

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 |

问题 I am trying to build a cypher query for two scenarios : Tests having depth more than 2 Specific test having depth more than 2 As in Image you can see tests 1, 2, 3 are somewhat related through depth more than 2. The cypher which i ran was : MATCH p=()<-[r:TEST_FOR*..10]-() RETURN p LIMIT 50 Now when i Change my cypher to below then i get no records/results or nodes. 1) MATCH p=()<-[r:TEST_FOR*2..5]-() RETURN p LIMIT 50 2) MATCH p=()<-[r:TEST_FOR*2]-() RETURN p LIMIT 50 3) MATCH p=(d:Disease)<

问题 Can you please explain why I run into this alert message of circular dependency when I try to create relationship between dimension #product (or #region) and a #bridge table which is a Cartesian of product x region? I have connected #bridge with Sales and Budget by single column P@G witch is concatenation of product and region. Download file here: PBIX 回答1: A quick and dirty solution is to creat to new versions of #product and #region by using VALUES . This is probably not the best way of

问题 I want to get the title, description, and price which are stored in a pivot table between users and services called userservices. I want to be able to display this information I'll get from the userservices table, inside the user profile view page. I have 4 tables for that which include, A User table with id, name, surname, email, phone, area_id. A Service table with id, name, description, and category_id. A category table with id, name, description and I have pivot table btw users and

问题 I have a linked table to a Outlook Mailitem folder in my Access Database. This is handy in that it keeps itself constantly updated, but I can't add an extra field to relate these records to a parent table. My workaround was to put an automatically generated/added ID String into the Subject so I could work from there. In order to make my form work the way I need it to, I'm trying to create a query that takes the fields I need from the linked table and adds a calculated field with the extracted

问题 My Item.orm.yml: AppBundle\Entity\Item: type: entity manyToMany: categories: targetEntity: AppBundle\Entity\Category cascade: ['persist'] inversedBy: items joinTable: name: item_category joinColumns: item_id: referencedColumnName: id inverseJoinColumns: category_id: referencedColumnName: id oneToMany: attributes: targetEntity: AppBundle\Entity\AttrValue mappedBy: item cascade: ['persist','remove'] table: items repositoryClass: AppBundle\Repository\ItemRepository id: id: type: integer id: true

问题 I have a list x here: I want to show the relationship between the elements like this: Can anyone tell me how to do this in R? Thank you very much! 回答1: First, build a matrix of all pairs from your original list: L <- list(c("John", "Mary", "Jack"), c("John", "Wendy"), c("Mary", "Wendy")) x <- matrix(unlist(lapply(L, combn, 2, simplify = FALSE)), ncol = 2) Then, use one of the methods shown here: Pairwise interaction matrix in R. I like the one using graph theory tools :-) library(igraph) g <-

问题 I have a Post model, and a Comment model that belongs to Post. I was able to display the Post in the home view corresponding to the home controller and home action and the User/show view. Thus, in the home and user views, the posts are listed in order of creation time. I was also able to have a post form in both the user and home views and a comment form in the home and user views. The problem arises when I try to display the comment underneath each displayed Post in the home and user views.

问题 I have Locations model which hasMany Employees -- similarly Employees belongsTo Locations This is nice and works well, but then I looked at adding PhoneNumbers . Either a Location or an Employee could have a phone number (office numbers versus personal numbers) Logically: Locations hasMany PhoneNumbers (multiple office lines) and Employees hasMany PhoneNumbers (home / cell ?) However when you create a hasMany relationship like this in Laravel it adds a field to the PhoneNumbers table. So we