The SQL IDE for Your Terminal.

After installing Python 3.8 or above, install Harlequin using pip or pipx with:

pipx install harlequin

From any shell, to open one or more DuckDB database files:

harlequin "path/to/duck.db" "another_duck.db"

To open an in-memory DuckDB session, run Harlequin with no arguments:

harlequin

If you want to control the version of DuckDB that Harlequin uses, see the Troubleshooting page.

Harlequin also ships with a SQLite3 adapter. You can open one or more SQLite database files with:

harlequin -a sqlite "path/to/sqlite.db" "another_sqlite.db"

Like DuckDB, you can also open an in-memory database by omitting the paths:

harlequin -a sqlite

Other adapters can be installed using pip install <adapter package> or pipx inject harlequin <adapter package>, depending on how you installed Harlequin. For a list of known adapters provided either by the Harlequin maintainers or the broader community, see the adapters page in the docs.

To view all command-line options for Harlequin and all installed adapters, after installation, simply type:

harlequin --help

To view a list of all key bindings (keyboard shortcuts) within the app, press F1. You can also view this list outside the app in the docs.

Visit harlequin.sh for an overview of features and full documentation.

Thanks for your interest in Harlequin! Harlequin is primarily maintained by Ted Conbeer, but he welcomes all contributions and is looking for additional maintainers!

We'd love to hear from you! Open an Issue to request new features, report bugs, or say hello.

1. Install Poetry v1.2 or higher if you don't have it already. You may also need or want pyenv, make, and gcc.
2. Fork this repo, and then clone the fork into a directory (let's call it harlequin), then cd harlequin.
3. Use poetry install --sync to install the project (editable) and its dependencies (including all test and dev dependencies) into a new virtual env.
4. Use poetry shell to spawn a subshell.
5. Type make to run all tests and linters, or run pytest, black ., ruff . --fix, and mypy individually.

1. PRs should be motivated by an open issue. If there isn't already an issue describing the feature or bug, open one. Do this before you write code, so you don't waste time on something that won't get merged.
2. Ideally new features and bug fixes would be tested, to prevent future regressions. Textual provides a test harness that we use to test features of Harlequin. You can find some examples in the tests directory of this project. Please include a test in your PR, but if you can't figure it out, open a PR to ask for help.
3. Open a PR from your fork to the main branch of tconbeer/harlequin. In the PR description, link to the open issue, and then write a few sentences about why you wrote the code you did: explain your design, etc.
4. Ted may ask you to make changes, or he may make them for you. Don't take this the wrong way -- he values your contributions, but he knows this isn't your job, either, so if it's faster for him, he may push a commit to your branch or create a new branch from your commits.