database-scout
Read-only exploration tool for SQLite / PostgreSQL databases — inspect table schemas, preview data, generate ER diagrams, and run safe queries.
Feature Overview
| Feature | Description |
|---|
| List all tables | Show tables and views in the database, with row counts |
| Inspect table schema | Column names, types, constraints (PK/FK/NOT NULL), indexes, defaults |
| Data preview | View the first N rows of a table |
| ER diagram generation | Output Mermaid erDiagram syntax, ready to render |
| Safe read-only queries | Only SELECT/WITH/EXPLAIN allowed; write operations are blocked |
Security Mechanisms
- Connection-level read-only: SQLite opens with
?mode=ro URI; PostgreSQL uses SET SESSION READ ONLY
- SQL whitelist: Only statements starting with SELECT / WITH / EXPLAIN / PRAGMA / SHOW are allowed
- Dangerous keyword blocking: INSERT, UPDATE, DELETE, DROP, ALTER, CREATE, and 30+ other keywords are blocked
- Multi-statement blocking: Semicolon-separated multiple SQL statements are rejected (prevents injection)
- Identifier escaping: Table names are double-quote escaped to prevent SQL injection
Quick Start
# List all tables in a SQLite database
python3 scripts/db_explorer.py --db-path data.db list-tables
# Inspect table schema
python3 scripts/db_explorer.py --db-path data.db describe users
# Preview data (default 20 rows)
python3 scripts/db_explorer.py --db-path data.db preview orders --limit 10
# Generate Mermaid ER diagram
python3 scripts/db_explorer.py --db-path data.db er-diagram
# Run a read-only query
python3 scripts/db_explorer.py --db-path data.db query "SELECT name, age FROM users WHERE age > 18 LIMIT 10"
PostgreSQL
# Connect to PostgreSQL
python3 scripts/db_explorer.py --db-type postgres --dsn "host=localhost dbname=mydb user=reader" list-tables
# Inspect table schema
python3 scripts/db_explorer.py --db-type postgres --dsn "host=localhost dbname=mydb user=reader" describe orders
Detailed Usage
Parameters
| Parameter | Required | Default | Description |
|---|
--db-type | No | sqlite | Database type: sqlite or postgres |
--db-path | Yes (for SQLite) | — | Path to the SQLite database file |
--dsn | Yes (for PostgreSQL) | — | PostgreSQL connection string |
Subcommands
| Command | Description | Example |
|---|
list-tables | List all tables/views | list-tables |
describe <table> | Show detailed table schema | describe users |
preview <table> [--limit N / -n N] | Preview the first N rows | preview orders --limit 5 |
er-diagram | Generate Mermaid ER diagram | er-diagram |
query "<sql>" | Run a read-only SQL query | query "SELECT count(*) FROM users" |
Output Examples
list-tables
[
{"name": "users", "type": "table", "row_count": 1500},
{"name": "orders", "type": "table", "row_count": 8200},
{"name": "user_stats", "type": "view", "row_count": 1500}
]
describe
{
"table": "orders",
"row_count": 8200,
"columns": [
{"cid": 0, "name": "id", "type": "INTEGER", "notnull": true, "default": null, "primary_key": true},
{"cid": 1, "name": "user_id", "type": "INTEGER", "notnull": true, "default": null, "primary_key": false},
{"cid": 2, "name": "amount", "type": "REAL", "notnull": false, "default": "0.0", "primary_key": false}
],
"foreign_keys": [
{"from": "user_id", "to_table": "users", "to_column": "id"}
],
"indexes": [
{"name": "idx_orders_user_id", "unique": false, "columns": ["user_id"]}
]
}
er-diagram (Mermaid)
erDiagram
users {
INTEGER id PK
TEXT name
TEXT email
INTEGER age
}
orders {
INTEGER id PK
INTEGER user_id FK
REAL amount
TEXT created_at
}
users ||--o{ orders : "user_id"
Dependencies
- Python 3.8+ (
sqlite3 is a built-in module)
- PostgreSQL support requires:
pip install psycopg2-binary
