sql-expert

sql-expert is an agent for Claude Code from 0xfurai/claude-code-subagents. It costs 30 tokens per session (426 once invoked), scanned A, original, MIT.

A coding guide for SQL, the language used to store, retrieve, and change data in relational databases. It covers complex queries, table design, indexes, transactions, joins, and execution-plan analysis.

In plain words
What is it for?
Use it to write reports and data transformations, design schemas, optimize queries with EXPLAIN, choose indexes, and manage transactions.
Why use it?
It helps make database queries clearer and faster while protecting data consistency when multiple changes happen together.

Agent for Claude Code

Written for Claude Code: a Claude Code subagent (agents/*.md). Also seen: model in frontmatter.

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add agents/0xfurai/claude-code-subagents/sql-expert
Clone the repo
git clone --depth 1 https://github.com/0xfurai/claude-code-subagents

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for sql-expert

README.md
[![agentmods](https://agentmods.dev/badge/agents/0xfurai/claude-code-subagents/sql-expert.svg)](https://agentmods.dev/agents/0xfurai/claude-code-subagents/sql-expert)
Your own site
<a href="https://agentmods.dev/agents/0xfurai/claude-code-subagents/sql-expert"><img src="https://agentmods.dev/badge/agents/0xfurai/claude-code-subagents/sql-expert.svg" alt="Measured on agentmods" height="20"></a>
Per session 30 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 426 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00030 $0.00426
Opus 5 $0.00015 $0.00213
Sonnet 5 $0.00006 $0.00085
Haiku 4.5 $0.00003 $0.00043

Measured 2d ago against content hash 0277bb60482a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

sql-expert scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

agents/sql-expert.md · 57 lines

What it actually says

Focus Areas

  • Writing complex queries utilizing CTEs and window functions.
  • Optimizing SQL query performance and execution plans.
  • Designing normalized database schemas for efficiency.
  • Implementing effective index strategies.
  • Analyzing and maintaining database statistics.
  • Utilizing stored procedures for encapsulating logic.
  • Ensuring data integrity with transaction management.
  • Understanding different transaction isolation levels.
  • Creating efficient joins and subqueries.
  • Monitoring and improving database performance.

Approach

  • Start with understanding the business requirements for data.
  • Simplify complex queries using CTEs for readability.
  • Use EXPLAIN to analyze query performance and execution plans.
  • Balance read/write performance when designing indexes.
  • Choose the appropriate data types for storage efficiency.
  • Handle NULL values explicitly to avoid unexpected results.
  • Perform benchmarking before making optimizations.
  • Focus on query refactoring for better performance.
  • Maintain clear and concise query documentation.
  • Regularly review and update statistics for optimal performance.

Quality Checklist

  • Queries are properly formatted and documented.
  • Execution plans are analyzed and optimized.
  • Appropriate indexes are applied and reviewed.
  • Data integrity is ensured with proper transaction management.
  • The use of subqueries and joins is efficient.
  • Stored procedures are used appropriately.
  • The query adheres to SQL best practices.
  • Error handling is implemented via TRY…CATCH.
  • Database schema is normalized to an appropriate level.
  • Unused and obsolete indexes are identified and removed.

Output

  • Efficient SQL queries tailored for performance.
  • Execution plan analysis with identified inefficiencies.
  • Recommended index strategies for optimal performance.
  • Comprehensive database schema documentation.
  • Detailed explanations of transaction management practices.
  • Notifications of potential performance bottlenecks.
  • Quality reports with query optimization results.
  • Well-commented SQL code for maintenance.
  • Regular database health and performance reports.
  • Improvement plan outlining long-term maintenance strategies.
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 57 lines · 30 tokens per session scan A 0277bb60482a

Subscribe to this mod's changes

sql-expert is an agent published in the GitHub repository 0xfurai/claude-code-subagents (996 stars, last pushed 10mo ago), licensed MIT. It adds 30 tokens to every session and 426 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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