95782bbca6
Added `english` / `spanish` tags and added `english` tag to template
1.2 KiB
1.2 KiB
tags |
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database, potsgresql, transaction, sql, english |
The WITH statement
Allows to save into variables tables results returned from a SELECT
or INSERT ... RETURNING statement, and use them in following querys.
Also allows to chain multiple INSERTS
, and if any of them fails, all previous INSERTS
are rolledback.
Note: autoincrements still increase on failures, hence skipped.
So It's excellent to avoid explicitly using transactions
Example
WITH inserted_user as (
INSERT INTO users (username, name, password_hash)
VALUES ('master', 'master', '$argon2i$v=19$m=4096,t=10,p=1$l9mKHF/++OJO4Fzj5VvOxw$smezKrrynx74W2+7L4zyiKUXWFdQDqdKf2RBMU4p0JI')
RETURNING user_id
), inserted_role as (
INSERT INTO roles (name)
VALUES ('master')
RETURNING role_id
), t as (
INSERT INTO join_users_roles (user_id, role_id)
SELECT user_id, role_id
FROM inserted_user, inserted_role
)
INSERT INTO join_roles_permissions (role_id, permission_id)
SELECT role_id, permission_id FROM inserted_role, permissions;
What led to learning this
- Needed to insert a bunch of data atomically accross many tables, see the example above. Working on a tiny family project