I had two models(Reporter and Article). I did
makemigrations
migrate
it created two tables in the database. Then I accidentally dropped the tables from the database.
Now, when I do migrate again, it says that the table does not exist. It does not create tables from models. The error message is:
relation "first_test_article" does not exist
What am I missing here?
Your last migration is that creates these tables?
The problem is that if you will migrate backwards to previous, exception will probably raise, because it will be trying to delete inexistent tables.
The way you can solve it is to create these tables (empty, without fields) by hands, then you should migrate backwards to previous migration. It will delete these tables, and then you will be able to migrate forwards and create these tables again.
Related
For a project i need to to delete all data from all tables in a database,
I tried
DELETE FROM table1,table2,table3,...;
But it doesnt work. Any advice ? Thank
I would like to refer You to this related post
How do I use cascade delete with SQL Server?
as You will find there several possible solutions.
When using SQL it means that Your data is relations, which means most of the records are somehow related in the different tables and this relation is expressed with foreign keys. However when attempting to delete data which is id is related with data in another table a cascade deletion should be implemented, the other way around it is add additional boolean column named isDeleted(as example ofcourse) and just alter specific rows to true in this specific column and then filter by preferences. Hopefully I have managed somehow to provide with alternative and/or possible solution to Your problem.
Leaving also this link which gives some examples on cascade deletion and guide on how to implement it. ->
https://www.sqlshack.com/delete-cascade-and-update-cascade-in-sql-server-foreign-key/
P.S. also if You want just to DELETE all the data You can either use TRUNCATE TABLE or DROP DATABASE query. With the latest option You will have to recreate the database once more.
Because you want to delete all databases from all tables, you are essentially deleting the database.
The sqlite way of doing this is to just delete the database file.
In contrast to postgres or mongodb or most databases, sqlite doesn't have a server so no need to call DROP DATABASE.
As soon as the file is gone and you open the database from your application you will be in a blank state again.
I am working with EF Core 6.0 and SQL Server. I have an Articles table (with associated temporal table named ArticlesHistory).
My user can delete/modify their articles, and then undo the changes thanks to the temporal table.
However, now I want to create a feature that allows user to delete an article permanently.
So I wonder if there is any way that we can remove record in Articles table, without inserting historical record into ArticlesHistory table?
As stated I need help deleting all data from every table in a test database. There are 3477 tables and some of the tables were created by a past employee so I was unable to create a schema of the DB and recreate it empty.
Is there a fast way to delete all of the data and keep all of the tables and their structure? Also, I noticed when deleting data from the DB with Delete table_name, that the data file wasn't decreasing in size. Any reason why? Then I tried to just delete the data file to see what would happen and it erased everything, so i had to restore the test database. Now I'm back at block one....
Any help or guidance would be appreciated.... I've read a lot and everything just says use Delete or Truncate, but rather not do that for 3477 tables.
The TRUNCATE TABLE command deletes the data inside a table, but not the table itself.
You have a lot of tables (more than 3000...), so take a look to following link to truncate all tables:
Truncate all tables in a SQL Server database
What happens when I runned:
zcat /mnt/Postgres/restoreFile.gz | psql my_db
on the working database and after doing ALTER TABLE and other standard things there were problems with duplicated keys. When I stopped it and tried to insert into database then I got duplicates key error because of sequences and constraints. Seems like all data is in but what about the sequences. What really happend with that database?
A normal Postgres backup consists of table design (like create table) and data (like insert) statements. If you run it twice, most design statements will fail. The insert statements would succeed in so far as the data definition allows for duplicate rows.
So restoring a database to a production server would typically result in a lot of duplicate rows in tables without a primary key. Some design changes made after the backup (like changing the owner of a table) may be undone.
I created a SQL Server database first (2 tables) and then tried to load data through SSIS data flow task. At the last step an error has occurred.
When I remove a relationship between two tables in the database, the SSIS task is completed successfully and the data is loaded! But, after I load data into the tables, I can't create relationship between them.
Based on this you can conclude that a relationship can be created when there is no data in a table. Just to mention, data types are the same in both tables.
How could I work out a solution?
Thank you!
It seems the error in SSIS is due to a foreign key violation. The purpose of the foreign key relationship is to prevent you for loading bad data. When you loaded without the FK, you inserted bad data and cannot create a (trusted) foreign key constraint afterward.
The solution is to either fix the source data or modify your package to avoid inserted data that doesn't exist in the referenced table. The latter can be done with a lookup task, sending found rows down the happy path to the target table. You could either ignore not found rows or write those to an error table or file.