Pair employees with their managers.
SQL: Alias a table twice to represent two different roles in one relationship.
CREATE TABLE employees (id INTEGER PRIMARY KEY,name VARCHAR(30),manager_id INTEGER);
INSERT INTO employees VALUES (1,'Ada',NULL),(2,'Grace',1),(3,'Lin',1);
SELECT e.name,m.name FROM employees e JOIN employees m ON m.id=e.manager_id ORDER BY e.id;Expected output EXAMPLE
Grace|Ada Lin|Ada
Details
Run in a scratch SQL database. These portable examples are executed on both PostgreSQL and SQLite. Result rows below use | between columns, without headers; client display formatting may differ. Alias a table twice to represent two different roles in one relationship. The CREATE and INSERT statements provide all input data. Run the complete example in a fresh scratch database or schema.
Tested on Ubuntu 24.04.5 LTS · · SQLite 3.45.1; PostgreSQL 18.6 (Debian 18.6-1.pgdg13+2) · bash 5.2.21-2ubuntu4; coreutils 9.4-3ubuntu6.3; psycopg 3.2.10; pymssql 2.3.8
Test inputs, results and environment
The exact published code ran in a dedicated Linux test container with prepared inputs. Snippet process uid 65534 with a read-only root filesystem and temporary working files. Database services use a private internal Docker network without published ports. Fresh scratch schema/database for each case; test database administrator credentials are confined to these disposable services. Fixtures and output records are isolated from the application database. Testing covers this example and its stated checks, not every input, operating system, or runtime version. The Linux container shares its host's kernel; this is not a native Windows test.
- Architecture / host kernel
- x86_64 / 6.18.54.1-microsoft-standard-WSL2
- Snippet identity / locale
- uid=65534, gid=65534 (unprivileged process) / C.UTF-8
- Interpreter invocation
Execute the exact SQL in a fresh database/schema; serialize result rows with | separators- Container image ID
sha256:ec91410a8f6ec3e985830b5e3a0560306d36f8c1c5ccd91a6699abe707123fa3- Code SHA-256
b48c2383e0f323358373d125ce689d39724a7261a904e6fa1281beec47082aa3- Dependencies
- bash 5.2.21-2ubuntu4; coreutils 9.4-3ubuntu6.3; psycopg 3.2.10; pymssql 2.3.8
Test input setup
These are the prepared inputs used by the test harness. See Details above for the prerequisites and how to run this example.
# No input files required.
Observed standard output
Grace|Ada Lin|Ada
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.