What is dialect-tsql?

A set of rules for writing T-SQL, the SQL language used by SQL Server and Fabric Warehouse. It covers names, dates, text, calculations, null values, and conditional aggregation.

Writing read queries against Fabric Warehouse or SQL Server sources, including date handling, text matching, ratios, conditional aggregates, and nullable columns.

It helps queries follow the syntax and row-limit behavior accepted by these database systems, avoiding unsupported clauses and incorrect integer calculations.

dialect-tsql — Skill for Claude Code and Codex by calvinchengx

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.

Any agent

npx skills add calvinchengx/data-agent-service --skill dialect-tsql

Clone the repo

git clone --depth 1 https://github.com/calvinchengx/data-agent-service

Made for: Claude Code, Codex.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/calvinchengx/data-agent-service/dialect-tsql.svg)](https://agentmods.dev/skills/calvinchengx/data-agent-service/dialect-tsql)

Your own site

<a href="https://agentmods.dev/skills/calvinchengx/data-agent-service/dialect-tsql"><img src="https://agentmods.dev/badge/skills/calvinchengx/data-agent-service/dialect-tsql.svg" alt="Measured on agentmods" height="20"></a>

Per session 23 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 460 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

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.

Model	Per session	Once invoked
Fable 5.1	$0.00023	$0.00460
Opus 5	$0.00012	$0.00230
Sonnet 5	$0.00005	$0.00092
Haiku 4.5	$0.00002	$0.00046

Measured 7d ago against content hash ff40cdfff64a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

dialect-tsql 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 7d 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.

agent/skills/dialect-tsql/SKILL.md · 18 lines

What it actually says

Applies to sources whose dialect is tsql (list_sources reports it).

Row ceiling: the executor rewrites your SELECT to SELECT TOP (n). Do not write TOP, LIMIT, OFFSET … FETCH yourself; LIMIT is a syntax error here.
Identifiers: schema.table two-part names; quote with [brackets] only when a name needs it.
Dates: DATEFROMPARTS(y, m, d), DATEADD(unit, n, col), DATEDIFF(unit, a, b), EOMONTH(col). Year/month: YEAR(col), MONTH(col), or FORMAT(col, 'yyyy-MM') for a label. A fiscal calendar is a catalog definition — look for a calendar table or a metric expression before writing arithmetic.
Strings: CONCAT, LEN, + for concatenation; string literals in single quotes; LIKE is case-insensitive under the default collation, so do not add LOWER() unless the catalog says the column is case-sensitive.
Division: integer / integer is integer. Cast one side (CAST(x AS decimal(18,4)) or 1.0 * x) before any ratio.
Nulls in aggregates: AVG and SUM skip nulls; COUNT(col) skips nulls, COUNT(*) does not. Say which you used when the catalog flags a nullable column.
Conditional aggregation: SUM(CASE WHEN … THEN 1 ELSE 0 END), AVG(CASE WHEN … THEN 1.0 ELSE 0.0 END) for a rate.
Ordering: ORDER BY is allowed on the outer query only.
Not available on Fabric Warehouse: MERGE, temp tables, IDENTITY, SELECT INTO — none are needed for a read, and the guard refuses writes regardless.

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.

7d ago First seen · 18 lines · 23 tokens per session scan A ff40cdfff64a

Subscribe to this mod's changes

dialect-tsql is a skill published in the GitHub repository calvinchengx/data-agent-service (0 stars, last pushed yesterday), licensed Apache-2.0. It adds 23 tokens to every session and 460 once invoked, about $0.0001 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 2026-08-31.

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