With the ongoing database decomposition work, Most of our database tables have foreign keys. In GitLab,įoreign keys are vital part of the database design process. Two database tables together, and ensure data-consistency between them. You can view EDUCBA’s recommended articles for more information.In relational databases (including PostgreSQL), foreign keys provide a way to link
We hope that this EDUCBA information on “Postgres Delete Cascade” was beneficial to you. As shown above, the DELETE CASCADE can be used in PostgreSQL to delete all the child records whenever the referenced parent record is deleted automatically, which helps in maintaining integrity.
If the parent is not there, then there should not be any child records that are referencing the deleted records of the parent. It is extremely crucial to maintain consistency and cleanliness of the data in the database.
In the database structure, it is very important to consider the foreign relationships between the tables while performing any CRUD operations. Using DELETE CASCADE, developer records with team ID 2, like Payal and Sayali, will be deleted automatically. Now, we will delete all the records with team id as 2, that is, Inventory. However, as we are using the DELETE CASCADE, the record from the parent table and all the referencing records will be deleted. In normal case, if we delete the record from the parent table and child table containing referencing records, then it won’t allow deleting. Step 7: Now, we will learn how the delete cascade will be used and perform the delete operation on the above-created tables. Step 6: Let us check whether all the records are inserted correctly in the tables. Step 5: Let’s insert some referencing records in the child/referencing table of developers.Ĭode: INSERT INTO developers (developer_id, team_id, name, position, technology) VALUES Step 4: Now we will insert into the parent table teams some of the records.Ĭode: INSERT INTO teams (id, team_count, department) VALUES Team_id INTEGER REFERENCES teams (id) ON DELETE CASCADE, Here is the syntax using which we can do so while creating the developer’s table. Step 3: Now, if we want to delete the record from teams with a particular id along with all the referencing records of the developer’s table which are referencing the team record which is being deleted, then we will use DELETE CASCADE. When deleting a team record, the presence of referencing records in the developer’s table will prevent deletion due to the default DELETE value being DELETE RESTRICT. team_id will be our referencing key, which will refer to the id of the team table.Įxplanation: The above query will create just a referencing table ‘developers’ for teams. There will be one too many relationships between teams and developers’ tables. Step 2: Now, we will create a table for developers which will act as the referencing or child table. Step 1: Firstly, let us create a table for teams which will be our main referenced parent table. While maintaining both records in the database, we will first create tables for each one of them. Each developer belongs to one or the other team, and one team is made of many developers. The example will contain two tables, namely teams, and developers. Here, we will learn how we can use delete cascade in PostgreSQL with the help of an example. When we use the DELETE CASCADE feature, deleting the referenced entry (parent record) results in the automatic deletion of all its referencing records (child records). We can set up foreign keys to prevent manipulation of referenced records when there are corresponding referencing records in other tables. When we come across a table containing one or more records, where a field or group of fields uniquely represents records from another table, we assign the label of “referencing table” or “child table” to the first table and the label of “referenced table” or “parent table” to the table whose records are being referenced. Hence, it is first necessary to understand what is the foreign key.
POSTGRES ON UPDATE CASCADE HOW TO
How to use Postgres Delete Cascadeĭelete cascade is only used when the tables involve foreign key constraints. When we specify the foreign key constraint in the referencing table using the “ON DELETE CASCADE” keywords, it indicates that the operation performed on the referenced table should cascade to the referencing records.
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