Looping in SQL while creating a view - sql

Question

Im having a hard time looping using sql, the table Im using resources references itself by having a parent column so I want to do the following logic while creating the view in sql but I'm stuck...
since im using a left join between my auth_permissions table and resource table, we are always looking at a row of type 'table'
- for the current row in table resources which is always of type 'table'
- give me the rows parent which is in position resources[4]
- then go to the row where id is equal to resources[4] which is of type 'schema'. spit out the 'name' column
- then go to that rows parent which is of type 'database' and spit out the 'name' column
What my current sql query looks like
CREATE OR REPLACE VIEW dev.permissions
AS select
left(rls.name, length(rls.name) - 5) AS "users",
res.name as "table",
ap.p_create as "insert",
ap.p_read as "select",
ap.p_update as "update",
ap.p_delete as "delete"
FROM dev.auth_permissions ap
LEFT JOIN dev.roles rls ON rls.id = ap.role_id
LEFT JOIN dev.resources res ON res.id = ap.resource_id
The result of my SQL query
users table insert select update delete
student midterm false true false false
student midterm false true false false
teacher midterm true true true true
teacher midterm false true true true
sub midterm false true false false
sub midterm false true false false
This is what I want my view to look like / the final SQL query result
users database schema table insert select update delete
student PrivateDatabase English midterm false true false false
student PrivateDatabase Math midterm false true false false
teacher PrivateDatabase English midterm true true true true
teacher PrivateDatabase Math midterm false true true true
sub PrivateDatabase English midterm false true false false
sub PrivateDatabase Math midterm false true false false
The tables im using to create the view look like so
roles Table
id code name description
1 245 student null
2 411 teacher null
3 689 sub null
resources Table, the parent column references itself so that I can track the parent of a table or schema. But a database has no parent since its at the top of the hierarchy
id origin type name parent
1 PrivateDatabase database summer2020 null
2 PrivateDatabase schema English 1
3 PrivateDatabase table midterm 2
4 PrivateDatabase schema Math 1
5 PrivateDatabase table midterm 4
auth_permissions Table, role_id reference the roles table and resources reference the resources table
id role_id resource_id p_create p_read p_update p_delete
1 1 3 false true false false
2 1 5 false true false false
3 2 3 true true true true
4 2 5 true true true true
5 3 3 false true false false
6 3 5 false true false false
THANK YOU IN ADVANCE! Any feedback is appreciated!

Answer 1

You need to join the resources table twice more in your query to fetch the schema and database names. In each case you join the id to the previous instantiations parent value:
CREATE OR REPLACE VIEW permissions AS
SELECT
rls.name AS "users",
res3.name as "database",
res2.name as "schema",
res.name as "table",
ap.p_create as "insert",
ap.p_read as "select",
ap.p_update as "update",
ap.p_delete as "delete"
FROM auth_permissions ap
LEFT JOIN roles rls ON rls.id = ap.role_id
LEFT JOIN resources res ON res.id = ap.resource_id
LEFT JOIN resources res2 ON res2.id = res.parent
LEFT JOIN resources res3 ON res3.id = res2.parent
Sample query:
SELECT *
FROM permissions
Output (for your sample data)
users database schema table insert select update delete
student summer2020 English midterm false true false false
student summer2020 Math midterm false true false false
teacher summer2020 Math midterm true true true true
teacher summer2020 English midterm true true true true
sub summer2020 Math midterm false true false false
sub summer2020 English midterm false true false false
Note I've assumed you want the database name, not its origin. If you really want the origin value, just change res3.name in the query to res3.origin.