Include zero counts for missing relationships.
SQL Server: Count the non-null child key after a left join so a missing relationship produces zero.
CREATE TABLE people (id INTEGER PRIMARY KEY, name VARCHAR(30));
CREATE TABLE orders (id INTEGER PRIMARY KEY, person_id INTEGER, amount INTEGER);
INSERT INTO people VALUES (1,'Ada'),(2,'Grace'),(3,'Lin');
INSERT INTO orders VALUES (1,1,10),(2,1,20),(3,2,5);
SELECT p.name, COUNT(o.id) FROM people p LEFT JOIN orders o ON o.person_id=p.id GROUP BY p.id,p.name ORDER BY p.id;Expected output EXAMPLE
Ada|2 Grace|1 Lin|0
Details
Requires SQL Server 2022 or later. Run in an empty scratch database in SSMS or sqlcmd. Result rows below use | between columns, without headers; client display formatting may differ. Count the non-null child key after a left join so a missing relationship produces zero. 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 · · SQL Server 16.0.4295.3 · 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
83741bf2532dc380e404716fde3a0d47aa8dbbd1777adb836c79eaa3e753c0cb- 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
Ada|2 Grace|1 Lin|0
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.