foreign-keys

问题 I'm using Django 3.0.6 I'm adding ForeignKey and ManyToManyField to my models, but I've noticed that django creates the INDEX , but not the actual FOREIGN KEY constraints in the db. I've tried to explicitly set db_constraint=True but as expected is useless, since it's True by default. I've found so many answers explaining this, but only for very old Django versions, doing tricks for enabling it when it was otherwise disabled. Now instead it should just work out of the box. Couldn't find

问题 I have a question about database relationship I am trying to build a monitoring system with the following rules : Channels belongs to one Sensor Sensors belongs to one Device Devices belongs to one Probe Probes belongs to one Core Here is a preview of the tables +-------------+ +-------------+ | Cores | | Probes | +-------------+ +-------------+ | id | | id | | fields ... | | fields ... | +-------------+ | core_id | +-------------+ +-------------+ +-------------+ +-------------+ | Devices | |

问题 I have a question about database relationship I am trying to build a monitoring system with the following rules : Channels belongs to one Sensor Sensors belongs to one Device Devices belongs to one Probe Probes belongs to one Core Here is a preview of the tables +-------------+ +-------------+ | Cores | | Probes | +-------------+ +-------------+ | id | | id | | fields ... | | fields ... | +-------------+ | core_id | +-------------+ +-------------+ +-------------+ +-------------+ | Devices | |

问题 Microsoft has exposed the scriptdom API to parse and generate TSQL. I'm new to it and still playing with it. I want to know how to get the cross databases references from queries like this one. UPDATE t3 SET description = 'abc' FROM database1.dbo.table1 t1 INNER JOIN database2.dbo.table2 t2 ON (t1.id = t2.t1_id) LEFT OUTER JOIN database3.dbo.table3 t3 ON (t3.id = t2.t3_id) INNER JOIN database2.dbo.table4 t4 ON (t4.id = t2.t4_id) What I want is a list of the references: database1.dbo.table1.id

问题 I have the following models.py class Notebook(models.Model): category = models.ForeignKey(Category) title = models.CharField(max_length=200, help_text='Maximum 250 characters') slug = models.SlugField(unique=True) last_modified = models.DateTimeField() def __unicode__(self): return self.title class Page(models.Model): Notebook = models.ForeignKey(Notebook) title = models.CharField(max_length=200) slug = models.SlugField(unique_for_date='pub_date') tags = TaggableManager() pub_date = models

问题 I have the following models.py class Notebook(models.Model): category = models.ForeignKey(Category) title = models.CharField(max_length=200, help_text='Maximum 250 characters') slug = models.SlugField(unique=True) last_modified = models.DateTimeField() def __unicode__(self): return self.title class Page(models.Model): Notebook = models.ForeignKey(Notebook) title = models.CharField(max_length=200) slug = models.SlugField(unique_for_date='pub_date') tags = TaggableManager() pub_date = models

问题 I have created two tables and also created a relationship between them. Table students : create table students ( [StudentId] NVARCHAR(50) NOT NULL PRIMARY KEY, [Name] NVARCHAR(50) NOT NULL ); Table studentprofile : create table studentprofile ( [Id] INT NOT NULL PRIMARY KEY IDENTITY(1, 1), [StudentId] NVARCHAR(50) NOT NULL, [Address] NVARCHAR(50) NOT NULL, ); and relationship: alter table studentprofile add constraint students_studentprofile_FK foreign key (StudentId) references students

问题 In Postgres 10 I have declared the following: create table test_abc ( pk integer not null, id integer not NULL, id2 integer not null, PRIMARY KEY (pk) ); CREATE UNIQUE INDEX test_abc_ids ON test_abc(id,id2); And then a second table with a FK referencing the first: create table test_def ( id integer not null, abc_id integer, abc_id2 integer, PRIMARY KEY (id), FOREIGN KEY (abc_id,abc_id2) references test_abc(id,id2) ); Now consider the output of this query: SELECT unique_constraint_catalog,

问题 I can implement the constraints that I want in stored procs, but I'm wondering if I can define a set of foreign key constraints which will do the job. I have several tables, with these key relationships: NSNs --- Id PK Solicitations ---- Id PK NSNId FK - NSNs Parts ----- Id PK NSNId FK - NSNs BaseRFQs ------- Id PK NSNId FK - NSNs RFQs ---- Id PK BaseRFQId FK - BaseRFQs BaseRFQsSols ------------ BaseRFQId PK/FK - BaseRFQs SolId PK/FK - Solicitations RFQsSolsParts ------------- RFQId PK/FK -

问题 I have added foreign keys to my project using sequelize. User is the parent table and profile_personals is the child table. When I post something the foreign key comes out as NULL. I'm trying to create it so when I post something through postman it can grab the User id Automatically. db.js file const db = {}; db.sequelize = sequelize; db.Sequelize = Sequelize; // Models db.Users = require('../model/User.js')(sequelize, Sequelize); db.Personal = require('../model/profile_personal.js')