So I have a disabled foreign key (Manager_ID in the table Employees) and I wanted to enable it, but I get this error: ORA-02298: cannot validate (my_username.EMP_MANAGER_FK) – parent keys not found And this is the code: Here’s how the table was created: Answer There are values in the column that a…
Tag: foreign-keys
Define Position based on lowest ID and Foreign Key in MySQL
I am currently facing the following issue: I have 1 Table with my Broker Trading Data similar to this: The Goal is to say IF first OrderType (lowest Id where TradeId is the same) was a Buy, it’s a LONG Trade ELSE a Short Trade … output should be like this: What am I missing? How can I construct my
PostgreSQL / express rookie – create new table or just a new column in existing table? [closed]
Closed. This question needs details or clarity. It is not currently accepting answers. Want to improve this question? Add details and clarify the problem by editing this post. Closed 2 years ago. Improve this question This will probably get closed for being opinion based but hopefully I can get a comment or t…
How to cascade on delete in a foreign key of a mysql table correctly?
I have three tables with foreign keys which should cascade on delete nevertheless when I run this only the mapping in Tagmap and nothing happens in Excerpt nor Tag. What am I doing wrong? Answer This is not how foreign keys work. You delete from the parent table (here, tag, or excerpt), and then children reco…
Major bug in MySQL 8.x? — foreign keys
While retrieving foreign keys information from MySQL (for a code generator) I noticed this strange behavior. It looks like a major bug in MySQL 8.x. When I create a foreign key using REFERENCES the …
MySQL (Percona) Error 1452: Cannot add or update a child row for no reason
I have 2 Database Tables “users” and “tasks”. The tasks table contains two foreign keys for the createdBy_user_id and updatedBy_user_id columns both referencing users.id. If I try to insert an entry to tasks (after making sure the user referenced by the foreign keys exists) like this: …
PostgreSQL cyclic foreign keys to multiple tables
I have 3 tables. chat_room group_chat_room private_chat_room As you can see chat_room has foreign key constraints that refer to group_chat_room and private_chat_room. Also both group_chat_room and private_chat_room have FK constraints that refer to chat_room. When I want to INSERT a row into group_chat_room I…
SQLite Delete row from Table A when columns are referenced as FOREIGN KEYS in other Tables B, C, etc
So I have several tables, but will show only 2 as an example: Table G gNo | gName | gAddress G1 | Jean | Bonalbo G2 | Oscar | Berlin G3 | Edd | Brisbane G4 | Bob | California Table B gNo | …
how to disallow custom lists to have elements from different base lists
I have the following model: BASE_LIST: in this table we store base lists. Base list can be for example the list of cities in a continent, types of automobiles in a shop etc. ELEMENT: in this table we store the elements of base lists. For example the cities and the car types are here (Budapest, London, Paris, …
Making sense of database table references with foreign and primary keys
I am relatively new to database logic, and am trying to figure out how multiple tables should/shouldn’t reference each other. I have a table, ‘Book’, that should have columns: I want each book to have the possibility to have 1 or more genres. I want each book to have the possibility to have …