Why in Sentry 2 database schema, relationships between tables don't exist? For example between users and users_groups table. Do I have to manually set that?
Sentry will create the needed tables for you so you do not nee to make any other changes.
There are no foreign keys if this is what you asking. Foreign keys are just way to help guarantee the data integrity and are not required.
Related
My question is related to the ER-diagram I designed using Oracle SQL developer. I designed this ER-diagram but I don't know how to read the relationships between these tables.
I have created this ER diagram:
ER Diagram
As it can be seen that these relations don't look like those normal one to many or many to one relations. Can anyone please help me how to read the relation between SYS.GENERAL_LEDGER_ACCOUNTS and SYS.INVOICE_LINE_ITEMS? Thanks in advance
The relationship is described by the foreign key:
ALTER TABLE invoice_line_items
ADD CONSTRAINT line_item_fk_accounts
FOREIGN KEY (account_number)
REFERENCES general_ledger_accounts(account_number);
Defines a foreign key with the name line_item_fk_accounts on the column account_number which references the account_number of the general_ledger_accounts.
Assuming that it is notNULL then this is a many-to-one relationship such that each row of invoice_line_items has a relationship to exactly one row in the general_ledger_accounts and there can be many invoice_line_items for each general_ledger_accounts.
Similarly, line_items_fk_invoices is a many-to-one constraint with many invoice_line_items each referencing one row of the invoices table.
Aside: NEVER modify the system schemas. If you do you risk making the database unusable and invalidating any support contract that you have with Oracle. Instead, you should create a user and then work in that schema.
Can someone suggest a way to generate delete queries for various tables linked via foreign key constrains for Oracle ? A solution for SQLServer is mentioned here
Copied description from the original question :
I have the table: DelMe(ID) and there are 30 tables with fk references
to its ID that I need to delete first, is there some tool/script that
I can run that will generate the 30 delete statements based on the FK
relations for me ?
(Laravel framework)
How to create tables in database with migrations so when I try to delete a row from a table that has its key as a foreign key somewhere in another table, I got an error from database not letting me to do that ?
Do I have to create relations in migrations where I say what are the foreign keys in my database, or is there another way using only Laravel models.
I am new with this. Thank you.
You need to remove deactivate the foreign key check so to say, I am using following function to accomplish that. First I set the Foreign key check to 0 then truncate the table and set it back to 1. Setting the foreign key check to 0 allows one to truncate the table even if there are foreign keys.
# functions to truncate users table even if there are foreign key
public static function truncateUserTable()
{
DB::statement('SET FOREIGN_KEY_CHECKS=0');
User::query()->truncate();
DB::statement('SET FOREIGN_KEY_CHECKS=1');
}
I was trying to create a hive table with a foreign key relationship with another table but I am facing errors with that.
Isn't it possible to implement a foreign key relationship in a hive table?
hive does not implement foreign keys refer to Hadoop Tutorials which describes as below:
Like any other SQL engines, we don't have any primary keys and foreign keys in Hive as hive is not meant to run complex relational queries. It's used to get data in easy and efficient manner. So while designing hive schema, we don't need to bother about selecting unique key etc. Also we don't need to bother about normalizing the set of data for efficiency.
I am working with Hibernate 4 and Spring 3.5 , so I want to do a delete operation in a table or entity, but a table has referential integrity with other tables. I want to know how I can know if a table has referential integrity, thus I can delete the record or not.
If there is a constraint and you are not aware and you try to delete a record that has a dependency to the other tables. You might get a ConstraintViolation Exception.
http://docs.oracle.com/javaee/6/api/javax/validation/ConstraintViolationException.html
Anyhow, I suggest you to look at table relationships (in the database) and make sure there is no PK/FK relationship before deleting any record.
Also if you are using JPA entities, you might have relationships in the JPA level (#OneToOne, #OneToMany, ...)