Add an optional field to an existing table.
SQL Server: A nullable column permits existing rows to remain valid while data is filled later.
CREATE TABLE sales (id INTEGER PRIMARY KEY, team VARCHAR(10), amount INTEGER, units INTEGER);
INSERT INTO sales VALUES (1,'A',10,2),(2,'A',20,1),(3,'B',30,3),(4,'B',40,2);
ALTER TABLE sales ADD note VARCHAR(30);
UPDATE sales SET note='checked' WHERE id=1;
SELECT id,note FROM sales WHERE id<=2 ORDER BY id;Expected output EXAMPLE
1|checked 2|NULL
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. A nullable column permits existing rows to remain valid while data is filled later. 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
1fc23279a1dbfcb578127b054738b893c5fbdb219cd16bcd321edc207cf7f0e0- 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
1|checked 2|NULL
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.