Hi Everybody, I am working with Python MySQL, and need to clean a table in my database that has 13328 rows. I can not make a simple drop table, because this table is child and also father of other child foreign-keys linked on it. If I try drop table, the system forbidden me. The table is defined with ON UPDATE CASCADE, ON DELETE CASCAD...
Hi I am trying to select count of rows from a table which has foreign keys of two tables. The C# code threw the error mentioned below. So, I added a primary key column to the table (schema as follows) and regenerated the code. But still the same error is coming. Error : Can't decide which property to consider the Key - you can create o...
Edited :-) Hopefully a bit clearer now. The logic is of the model is: A Building has many Rooms A Room may be inside another Room (a closet, for instance--ForeignKey on 'self') A Room can only in inside of another Room in the same building (this is the tricky part) Here's the code I have: #spaces/models.py from django.db i...
Having two tables, "users" and "lists", and a many-to-many "subscriptions" table relating users to lists (thus having foreign keys user_id and list_id), what would be a single SQL query to find all the users that don't have any subscription with a specific list_id (naturally including the users that have no subscriptions at all)? ...
I have a table following table create table tblcountry ( unqid uniqueidentifier name varchar(100) isremoved bit ) I want to create primary key on basis of unqid + isremoved and in which isremoved must be true i have got another table: create table tblstate ( unqid uniqueidentifier, name varchar(100) f_tblcountry uniquei...
When you study relational theory foreign keys are, of course, mandatory. But in practice, in every place I worked, table products and joins are always done by specifying the keys explicitly in the query, instead of relying on foreign keys in the DBMS. This way, you could of course join two tables by fields that are not meant to be for...
I have two tables 'Elements' and 'Lists' Lists has a primary key and a list name. Elements has data pertaining to an individual entry in the list. Elements needs a column that holds which list the element is in. I've read about SQL's foreign key constraint and figure that is the best way to link the tables, but I'm using SQLite which d...
I have the following table: CREATE TABLE child( id INTEGER PRIMARY KEY, parent_id INTEGER, description TEXT); How do I add a foreign key constraint on parent_id? Assume foreign keys are enabled. Most examples assume you're creating the table - I'd like to add the constraint to an existing one. ...
I am looking for code to generate a reproducible deadlock that occurs from the use of Cascading Constraints. I can find references online for the specific problem, and I have answered dozens of questions on deadlocks where cascading constraints were in use, but none of them has a reproducible version of the deadlock. I am not looking fo...
A beginners' question about foreign key in MySQL. In w3cshool it says, A FOREIGN KEY in one table points to a PRIMARY KEY in another table. And also there is WHERE, WHERE id = page_id So if I can use WHERE for linking the tables, what is the main purpose of having foreign key? ...
Hi, I am trying to create a foreign key constraint consisting of an int column and a datetime column (both not null). I am getting the error "There are no primary or candidate keys in the referenced table X that match the referencing column list in the foreign key FK". Normally this error means that the column(s) in the target table i...
This is what I had before (but realized that you can't obviously do it in this order: class MasterAdmin(models.Model): """ A permanent admin (one per Account) that shouldn't be deleted. """ admin = models.OneToOneField(AccountAdmin) class Account(models.Model): """ A top-level account in the system. """ ...
I have a SQL-Server 2008 database and a schema which uses foreign key constraints to enforce referential integrity. Works as intended. Now the user creates views on the original tables to work on subsets of the data only. My problem is that filtering certain datasets in some tables but not in others will violate the foreign key constrain...
Is there a way to get the foreign key type of the model my key relates to? Currently, I'm trying something like: def __init__(self, *args, **kwargs): super(JobOrderSupplementForm, self).__init__(*args, **kwargs) for field in self.fields: if type(self.fields[field]) == TypedChoiceField: fieldOp...
I'll be doing this in sqlite now that they support foreign keys and tsql and perhaps mysql. Is it illegal to do something like CREATE TABLE comment( id integer primary key, parent integer references(comment.id), author integer references(User.id), desc varchar(max), hidden bit deleted bit ); where parent may be 0 or null because it ...
I have two tables where foreign key cannot be set so is it necessary to assign foreign key any way? ...
While using SubSonic 3 i wrote the below. I thought i would get user_ref would be a column with name_list as its foriegn key. My database ended up with just id and link with only the image_list table. How can i have user_ref use name_list as its foriegn key and have both tables in the database? class image_list { public long ID { g...
Hello, Sometime you have many relationships in a table, and you need to insert data. It becomes a painful task when you constantly have to go check the ids of your parent rows for each foreign keys. Is there a tool that make this task easier, by allowing me to do a kind of ajax search for ids while I am inserting data? For exemple, ...
i have change name of table through procedure sp_rename.Do i need to change fk constraint of child table? ...
I have a table, let's call it Users. This table has primary key called Id. Despite having Id as primary key (unique clustered), it has other index (unique nonclustered) on the same column(Id). I would like to drop this constraint, but foreign keys reference this unique nonclustered index and I get The constraint ... is being referenced...