mssql

Execute read-only SQL queries against multiple Microsoft SQL Server databases. Use when: (1) querying MSSQL/SQL Server databases, (2) exploring database schemas/tables, (3) running SELECT queries for data analysis, (4) checking database contents. Supports multiple database connections with descriptions for intelligent auto-selection. Blocks all write operations (INSERT, UPDATE, DELETE, DROP, etc.) for safety.

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MSSQL Read-Only Query Skill

Execute safe, read-only queries against configured Microsoft SQL Server databases.

Requirements

Python 3.8+
pymssql: pip install -r requirements.txt

Setup

Create connections.json in the skill directory or ~/.config/claude/mssql-connections.json.

Security: Set file permissions to 600 since it contains credentials:

chmod 600 connections.json

{
  "databases": [
    {
      "name": "production",
      "description": "Main app database - users, orders, transactions",
      "host": "db.example.com",
      "port": 1433,
      "database": "app_prod",
      "user": "readonly_user",
      "password": "your-password",
      "encrypt": true,
      "tds_version": "7.3"
    }
  ]
}

Config Fields

Field	Required	Description
name	Yes	Identifier for the database (case-insensitive)
description	Yes	What data this database contains (used for auto-selection)
host	Yes	Database hostname
port	No	Port number (default: 1433)
database	Yes	Database name
user	Yes	Username
password	Yes	Password
encrypt	No	Enable TLS encryption (default: false)
tds_version	No	TDS protocol version: 7.0, 7.1, 7.2, 7.3, 7.4 (default: auto)

Usage

List configured databases

python3 scripts/query.py --list

Query a database

python3 scripts/query.py --db production --query "SELECT TOP 10 * FROM users"

List tables

python3 scripts/query.py --db production --tables

Show schema

python3 scripts/query.py --db production --schema

Limit results

python3 scripts/query.py --db production --query "SELECT * FROM orders" --limit 100

Note: MSSQL uses TOP N instead of LIMIT. The --limit flag automatically inserts TOP N after SELECT.

Database Selection

Match user intent to database description:

User asks about	Look for description containing
users, accounts	users, accounts, customers
orders, sales	orders, transactions, sales
analytics, metrics	analytics, metrics, reports
logs, events	logs, events, audit

If unclear, run --list and ask user which database.

Safety Features

Read-only enforcement: Query validation blocks write operations (use a db_datareader role user for server-side protection)
Query validation: Only SELECT, SHOW, EXPLAIN, WITH, SP_HELP queries allowed
Single statement: Multiple statements per query rejected
TLS support: Configurable encryption for secure connections
Query timeout: 30-second timeout enforced via pymssql
Connection timeout: 10-second login timeout
Memory protection: Max 10,000 rows per query to prevent OOM
Column width cap: 100 char max per column for readable output
Credential sanitization: Error messages don't leak passwords

Troubleshooting

Error	Solution
Config not found	Create `connections.json` in skill directory
Authentication failed	Check username/password in config
Connection timeout	Verify host/port, check firewall/VPN
TDS version error	Try `"tds_version": "7.3"` or `"7.4"`
Encryption error	Set `"encrypt": true` for Azure SQL
Permission warning	Run `chmod 600 connections.json`

Exit Codes

0: Success
1: Error (config missing, auth failed, invalid query, database error)

Workflow

Run --list to show available databases
Match user intent to database description
Run --tables or --schema to explore structure
Execute query with appropriate --limit (auto-converts to TOP N)

Repository: sanjay3290/ai-skills
Path: skills/mssql/SKILL.md
Commit: 281d88d

Last updated: 6 days ago
First committed: 8 months ago

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