attach-db
Attach a DuckDB database file for use with /duckdb-skills:query. Explores the schema (tables, columns, row counts) and writes a SQL state file so subsequent queries can restore this session automatically via duckdb -init.
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/duckdb/duckdb-skills --skill attach-db- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads attach-db automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
SKILL.md
The instructions your agent reads when the skill is triggered.
You are helping the user attach a DuckDB database file for interactive querying.
Database path given: $0
Follow these steps in order, stopping and reporting clearly if any step fails.
State file convention: see the "Resolve state directory" section below. All skills share a single state.sql file per project. Once resolved, any skill can use it with duckdb -init "$STATE_DIR/state.sql" -c "<QUERY>".
Step 1 — Resolve the database path
If $0 is a relative path, resolve it against $PWD to get an absolute path (RESOLVED_PATH).
RESOLVED_PATH="$(cd "$(dirname "$0")" 2>/dev/null && pwd)/$(basename "$0")"
Check the file exists:
test -f "$RESOLVED_PATH"
- File exists -> continue to Step 2.
- File not found -> ask the user if they want to create a new empty database (DuckDB creates the file on first write). If yes, continue. If no, stop.
Step 2 — Check DuckDB is installed
command -v duckdb
If not found, delegate to /duckdb-skills:install-duckdb and then continue.
Step 3 — Validate the database
duckdb "$RESOLVED_PATH" -c "PRAGMA version;"
- Success -> continue.
- Failure -> report the error clearly (e.g. corrupt file, not a DuckDB database) and stop.
Step 4 — Explore the schema
First, list all tables:
duckdb "$RESOLVED_PATH" -csv -c "
SELECT table_name, estimated_size
FROM duckdb_tables()
ORDER BY table_name;
"
If the database has no tables, note that it is empty and skip to Step 5.
For each table discovered (up to 20), run:
duckdb "$RESOLVED_PATH" -csv -c "
DESCRIBE <table_name>;
SELECT count() AS row_count FROM <table_name>;
"
Collect the column definitions and row counts for the summary.
Step 5 — Resolve the state directory
Check if a state file already exists in either location:
# Option 1: in the project directory
test -f .duckdb-skills/state.sql && STATE_DIR=".duckdb-skills"
# Option 2: in the home directory, scoped by project root path
PROJECT_ROOT="$(git rev-parse --show-toplevel 2>/dev/null || echo "$PWD")"
PROJECT_ID="$(echo "$PROJECT_ROOT" | tr '/' '-')"
test -f "$HOME/.duckdb-skills/$PROJECT_ID/state.sql" && STATE_DIR="$HOME/.duckdb-skills/$PROJECT_ID"
If neither exists, ask the user:
Where would you like to store the DuckDB session state for this project?
- In the project directory (
.duckdb-skills/state.sql) — colocated with the project, easy to find. You can choose to gitignore it.- In your home directory (
~/.duckdb-skills/<project-id>/state.sql) — keeps the project directory clean.
Based on their choice:
Option 1:
STATE_DIR=".duckdb-skills"
mkdir -p "$STATE_DIR"
Then ask: "Would you like to gitignore .duckdb-skills/?" If yes:
echo '.duckdb-skills/' >> .gitignore
Option 2:
PROJECT_ROOT="$(git rev-parse --show-toplevel 2>/dev/null || echo "$PWD")"
PROJECT_ID="$(echo "$PROJECT_ROOT" | tr '/' '-')"
STATE_DIR="$HOME/.duckdb-skills/$PROJECT_ID"
mkdir -p "$STATE_DIR"
Step 6 — Append to the state file
state.sql is a shared, accumulative init file used by all duckdb-skills. It may already contain macros, LOAD statements, secrets, or other ATTACH statements written by other skills. Never overwrite it — always check for duplicates and append.
Derive the database alias from the filename without extension (e.g. my_data.duckdb → my_data). Check if this ATTACH already exists:
grep -q "ATTACH.*RESOLVED_PATH" "$STATE_DIR/state.sql" 2>/dev/null
If not already present, append:
cat >> "$STATE_DIR/state.sql" <<'STATESQL'
ATTACH IF NOT EXISTS 'RESOLVED_PATH' AS my_data;
USE my_data;
STATESQL
Replace RESOLVED_PATH and my_data with the actual values. If the alias would conflict with an existing one in the file, ask the user for a name.
Step 7 — Verify the state file works
duckdb -init "$STATE_DIR/state.sql" -c "SHOW TABLES;"
If this fails, fix the state file and retry.
Step 8 — Report
Summarize for the user:
- Database path: the resolved absolute path
- Alias: the database alias used in the state file
- State file: the resolved
STATE_DIR/state.sqlpath - Tables: name, column count, row count for each table (or note the DB is empty)
- Confirm the database is now active for
/duckdb-skills:query
If the database is empty, suggest creating tables or importing data.
FAQ
What does the attach-db skill do?
Attach a DuckDB database file for use with /duckdb-skills:query. Explores the schema (tables, columns, row counts) and writes a SQL state file so subsequent queries can restore this session automatically via duckdb -init.
How do I install attach-db?
Run npx skills add https://github.com/duckdb/duckdb-skills --skill attach-db in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/attach-db/ (personal) or .claude/skills/attach-db/ (project).
Which AI agents can use attach-db?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is attach-db safe to install?
No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.
Who maintains attach-db?
It is published by duckdb in duckdb/duckdb-skills. It has 1,041 recorded installs.
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