duckdb-en

# DuckDB CLI Specialist

Helps with data analysis, SQL queries and file conversion via DuckDB CLI.

## Quick Start

### Read data files directly with SQL
```bash
# CSV
duckdb -c "SELECT * FROM 'data.csv' LIMIT 10"

# Parquet
duckdb -c "SELECT * FROM 'data.parquet'"

# Multiple files with glob
duckdb -c "SELECT * FROM read_parquet('logs/*.parquet')"

# JSON
duckdb -c "SELECT * FROM read_json_auto('data.json')"
```

### Open persistent databases
```bash
# Create/open database
duckdb my_database.duckdb

# Read-only mode
duckdb -readonly existing.duckdb
```

## Command Line Arguments

### Output formats (as flags)
| Flag | Format |
|------|--------|
| `-csv` | Comma-separated |
| `-json` | JSON array |
| `-table` | ASCII table |
| `-markdown` | Markdown table |
| `-html` | HTML table |
| `-line` | One value per line |

### Execution arguments
| Argument | Description |
|----------|-------------|
| `-c COMMAND` | Run SQL and exit |
| `-f FILENAME` | Run script from file |
| `-init FILE` | Use alternative to ~/.duckdbrc |
| `-readonly` | Open in read-only mode |
| `-echo` | Show commands before execution |
| `-bail` | Stop on first error |
| `-header` / `-noheader` | Show/hide column headers |
| `-nullvalue TEXT` | Text for NULL values |
| `-separator SEP` | Column separator |

## Data Conversion

### CSV to Parquet
```bash
duckdb -c "COPY (SELECT * FROM 'input.csv') TO 'output.parquet' (FORMAT PARQUET)"
```

### Parquet to CSV
```bash
duckdb -c "COPY (SELECT * FROM 'input.parquet') TO 'output.csv' (HEADER, DELIMITER ',')"
```

### JSON to Parquet
```bash
duckdb -c "COPY (SELECT * FROM read_json_auto('input.json')) TO 'output.parquet' (FORMAT PARQUET)"
```

### Convert with filtering
```bash
duckdb -c "COPY (SELECT * FROM 'data.csv' WHERE amount > 1000) TO 'filtered.parquet' (FORMAT PARQUET)"
```

## Dot Commands

### Schema inspection
| Command | Description |
|---------|-------------|
| `.tables [pattern]` | Show tables (with LIKE pattern) |
| `.schema [table]` | Show C...

# DuckDB CLI AI Skill

A comprehensive AI skill for [Claude Code](https://claude.ai/code) that provides expert assistance with DuckDB CLI operations.

## What is this?

This is a **skill file** for Claude Code (Anthropic's CLI tool). When activated, it gives Claude deep knowledge about DuckDB CLI, enabling it to help you with:

- SQL queries on CSV, Parquet, and JSON files
- Data conversion between formats
- Database operations and analysis
- Command-line arguments and dot commands
- Output formatting and configuration

## Installation

### Claude Code (recommended)

Copy `SKILL.md` to your Claude Code skills directory:

```bash
mkdir -p ~/.claude/skills/duckdb
cp SKILL.md ~/.claude/skills/duckdb/
```

Then use `/duckdb` in Claude Code to activate the skill.

### Other AI Tools

The `SKILL.md` file follows standard markdown conventions and can be adapted for use with other AI assistants that support custom instructions or system prompts.

## What's Included

The skill covers all official DuckDB CLI documentation:

- **Quick Start** - Read files directly with SQL
- **Command Line Arguments** - All flags and options
- **Data Conversion** - CSV, Parquet, JSON transformations
- **Dot Commands** - Schema inspection, output control
- **Output Formats** - All 18 available formats
- **Keyboard Shortcuts** - Navigation, history, editing
- **Autocomplete** - Context-aware completion
- **Configuration** - ~/.duckdbrc settings
- **Safe Mode** - Restricted file access mode

## Example Usage

Once the skill is activated, you can ask Claude things like:

- "Convert this CSV to Parquet"
- "Show me statistics for sales.csv"
- "Join these two files on customer_id"
- "What's the DuckDB command to export as JSON?"

## Documentation Sources

Based on official DuckDB documentation:
- [CLI Overview](https://duckdb.org/docs/stable/clients/cli/overview)
- [Arguments](https://duckdb.org/docs/stable/clients/cli/arguments)
- [Dot Commands](https://duckdb.org/docs/stable/clients/cli/dot_command...