Combine results without duplicates.
Merge compatible result sets with UNION.
CREATE TABLE products (id INTEGER PRIMARY KEY, name VARCHAR(40), category VARCHAR(20), price INTEGER);
INSERT INTO products VALUES (1, 'Pen', 'office', 3), (2, 'Book', 'office', 12), (3, 'Mug', 'kitchen', 8);
SELECT category FROM products WHERE id <= 2
UNION
SELECT category FROM products WHERE id >= 2
ORDER BY category;Expected output EXAMPLE
kitchen office
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. UNION removes duplicates. Use UNION ALL when repeated rows should be retained. The CREATE and INSERT statements supply the complete example data; use a fresh database or remove those setup statements when adapting the query.
Tested on Ubuntu 24.04.5 LTS · · SQLite 3.45.1; PostgreSQL 18.6 (Debian 18.6-1.pgdg13+2) · sqlite3 3.45.1-1ubuntu2.8; 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
ca36c1ebd1bd3911ea0b614f3f3d95849fb8a1c1511e236224b2cccf9b7d2553- Dependencies
- sqlite3 3.45.1-1ubuntu2.8; 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
kitchen office
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.