-- 假设有两个表 orders 和 products CREATE TABLE products ( product_id INT, category_id INT, PRIMARY KEY (product_id, category_id) ); CREATE TABLE orders ( order_id INT, product_id INT, category_id INT, FOREIGN KEY (product_id, category_id) REFERENCES products(product_id, category_id...
If you create an abstract model with 2 foreign keys (or generic relationships) to the same model and then inherit from the abstract model more than once you end up with "clashes with related field" errors. Here is an example models.py: from django.db import models class Foo(models.Model...
1452 - Can't write; duplicate in table '#sql-3e89_a4和1452 - Canot add or update a child row:解决办法,程序员大本营,技术文章内容聚合第一站。
Suppose you have a database that stores sales proposals. Suppose further that each proposal only has one sales person assigned and one client. So your proposal table would have two foreign keys, one with the client ID and one with the sales rep ID. However, at the time the record is cre...
how to check if columns in table was used as foreign key in other tables Not sure why no one suggested but I usesp_fkeysto query foreign keys for a given table: EXECsp_fkeys'TableName' You can also specify the schema: EXECsp_fkeys@pktable_name='TableName',@pktable_owner='dbo' ...
So, I know that you cannot use ALTER TABLE ... change column ... to rename a column when foreign keys depend on a column. However, you can use ALTER TABLE ... RENAME ... to rename the entire table, and ALL the foreign keys are updated. Why is that? I...
TYPE Here are the different values of the TYPE directive, default is TABLE: - TABLE: Extract all tables with indexes, primary keys, unique keys, foreign keys and check constraints. - VIEW: Extract only views. - GRANT: Extract roles converted to Pg groups, users and grants on all objects....
" We can only appreciate the miracle of a sunrise if we have waited in the darkness." Sapna Reddy
We still have two hours. Text 4 M: I am so tired of driving all those hours to work. W: Yeah. I know what you mean. I used to drive two hours to work each way. But now, I live within walking distance of my office. I don’t even need a bike. Text 5 W: Hi, Andy. I ...
mysql Can I have null values in a junction table with more than two foreign keys?Use a ...