foreign-keys

问题 I have created an EER diagram (as shown in the image bellow) in MySQL Workbench and wanted to Forward Engineer to build the DB. After configuring the model options to the Target MySQL Version and removing the word "Visible" from all the Indexes in the SQL Code (the code goes in the bottom of this post), as it was triggering an error, I have came across a 1005 Error: Executing SQL script in server ERROR: Error 1005: Can't create table `books`.`books` (errno: 150 "Foreign key constraint is

问题 New to Django and Python and I need a little help with a foreign key drop down. Basically, I have a category model and a image model and I want users to be able to choose which category to put the image in. How do I create a drop down for the category in the image form? Are my views and html correct too? I have had a look online but I can't seem to do it myself. I keep getting errors. Here are my models: class Images(models.Model): image = models.ImageField(upload_to='images', blank=False)

问题 New to Django and Python and I need a little help with a foreign key drop down. Basically, I have a category model and a image model and I want users to be able to choose which category to put the image in. How do I create a drop down for the category in the image form? Are my views and html correct too? I have had a look online but I can't seem to do it myself. I keep getting errors. Here are my models: class Images(models.Model): image = models.ImageField(upload_to='images', blank=False)

问题 I'm trying to figure out the best way to move/merge a couple tables of worth of data from multiple databases into one. I have a schema similar to the following: CREATE TABLE Products( ProductID int IDENTITY(1,1) NOT NULL, Name varchar(250) NOT NULL, Description varchar(1000) NOT NULL, ImageID int NULL ) CREATE TABLE Images ( ImageID int IDENTITY(1,1) NOT NULL, ImageData image NOT NULL ) With a foreign-key of the Products' ImageID to the Images' ImageID. So what's the best way to move the data

问题 I have one table Called Member with Column Name Member_Id . This Table Referred by more than 23 other tables as Primary Table with Member_Id as Foreign Column. Now these 23 tables also have Primary Keys, and some serve also as Primary table for other tables. So I want to fetch all Foreign Keys for all dependent Table referring to table Member . My Goal is to Truncate Member table which has Foreign keys. I can't use Delete as these tables have more data, so it may take ages for me to delete

问题 I have one table Called Member with Column Name Member_Id . This Table Referred by more than 23 other tables as Primary Table with Member_Id as Foreign Column. Now these 23 tables also have Primary Keys, and some serve also as Primary table for other tables. So I want to fetch all Foreign Keys for all dependent Table referring to table Member . My Goal is to Truncate Member table which has Foreign keys. I can't use Delete as these tables have more data, so it may take ages for me to delete

问题 This is a continuation of this question in which I am trying to figure out how to construct a PointField composed of lat / lon FloatFields. I have taken @Simon's advice and restructured my model to look like this: class Point(models.Model): lat = models.FloatField() lon = models.FloatField() class Thing(models.Model): point = models.ForeignKey(Point) My form has two fields corresponding to values from google maps' longitude and latitude coordinates: class StepThreeForm(forms.Form): lat =

问题 I've read a number of posts about this error, but none of the solutions have managed to solve the problem (assuming I've tried them correctly). This is the code that causes the error: CREATE TABLE season ( id smallint unsigned NOT NULL auto_increment, title varchar(25) NOT NULL, PRIMARY KEY (id) ); CREATE INDEX seasonId ON season(id); DROP TABLE IF EXISTS event; CREATE TABLE event ( id smallint unsigned NOT NULL auto_increment, title varchar(255) NOT NULL, season_id smallint NOT NULL, PRIMARY

问题 I'm trying to store arrays (or vectors) of data in a SQLite database but I'm having problems trying to find a decent way to do so. I found some other post on StackOverflow, that I can't seem to find anymore, which mentioned storing the data in a table like the following: CREATE TABLE array_of_points ( id integer NOT NULL, position integer NOT NULL, x integer NOT NULL, y integer NOT NULL, PRIMARY KEY (id, position) ); So to store all the data for a single array you would insert each item under

问题 I'm trying to store arrays (or vectors) of data in a SQLite database but I'm having problems trying to find a decent way to do so. I found some other post on StackOverflow, that I can't seem to find anymore, which mentioned storing the data in a table like the following: CREATE TABLE array_of_points ( id integer NOT NULL, position integer NOT NULL, x integer NOT NULL, y integer NOT NULL, PRIMARY KEY (id, position) ); So to store all the data for a single array you would insert each item under