Count the rows in a table.
SQL: COUNT(*) includes every row, including rows with NULL columns.
CREATE TABLE lesson_items (
id INTEGER PRIMARY KEY,
name VARCHAR(40) NOT NULL,
category VARCHAR(20),
quantity INTEGER NOT NULL
);
INSERT INTO lesson_items (id, name, category, quantity) VALUES
(1, 'Tea', 'Drinks', 4),
(2, 'Coffee', 'Drinks', 8),
(3, 'Bread', 'Food', 2),
(4, 'Water', NULL, 0);
SELECT COUNT(*) AS item_count FROM lesson_items;Expected output EXAMPLE
4
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.
Run each example independently in an empty scratch database or schema; the example includes its own starting table and rows.
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
50b668b86168f5bb1fe898f2e843bacb5674283819bfba33beb8976919337f73- 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
4
Exit code: 0. Standard error: empty. Validation: Exact stdout comparison. System-dependent values above are one recorded run.