tsql-functions

Q: How do I install tsql-functions?

Run npx skills add https://github.com/josiahsiegel/claude-plugin-marketplace --skill tsql-functions in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/tsql-functions/ (personal) or .claude/skills/tsql-functions/ (project).

by josiahsiegelData & Databases

Complete T-SQL function reference for SQL Server and Azure SQL Database. PROACTIVELY activate for: (1) string functions (CONCATWS, STRINGSPLIT, STRINGAGG, TRIM, REPLACE, LEFT/RIGHT/SUBSTRING), (2) date/time functions (DATEADD, DATEDIFF, FORMAT, DATETRUNC, AT TIME ZONE), (3) math and conversion functions (CAST, CONVERT, TRYCAST, ROUND, FLOOR, CEILING), (4) window/ranking functions (ROWNUMBER, RANK, LEAD/LAG, FIRSTVALUE, LASTVALUE, NTILE), (5) JSON functions (JSONVALUE, JSONQUERY, JSONMODIFY, OPENJSON), (6) XML functions (FOR XML, .nodes, .value), (7) aggregate functions and GROUP BY extensions, (8) system and metadata functions (sys. views, OBJECTID, OBJECTNAME). Provides: function catalog grouped by category, version-availability matrix (SQL 2016+/2019+/2022+), and worked examples for each function family.

Installs: 181
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Install

Works with every agent the skills CLI supports.

npx skills add https://github.com/josiahsiegel/claude-plugin-marketplace --skill tsql-functions

01
Install
Run the command in your project. The CLI asks which agents to install for.
02
Describe the task
Ask your agent for something this skill covers. It loads tsql-functions automatically when relevant.
03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.

SKILL.md

The instructions your agent reads when the skill is triggered.

T-SQL Functions Reference

Complete reference for all T-SQL function categories with version-specific availability.

Quick Reference

String Functions

Function	Description	Version
`CONCAT(str1, str2, ...)`	NULL-safe concatenation	2012+
`CONCAT_WS(sep, str1, ...)`	Concatenate with separator	2017+
`STRING_AGG(expr, sep)`	Aggregate strings	2017+
`STRING_SPLIT(str, sep)`	Split to rows	2016+
`STRING_SPLIT(str, sep, 1)`	With ordinal column	2022+
`TRIM([chars FROM] str)`	Remove leading/trailing	2017+
`TRANSLATE(str, from, to)`	Character replacement	2017+
`FORMAT(value, format)`	.NET format strings	2012+

Date/Time Functions

Function	Description	Version
`DATEADD(part, n, date)`	Add interval	All
`DATEDIFF(part, start, end)`	Difference (int)	All
`DATEDIFF_BIG(part, s, e)`	Difference (bigint)	2016+
`EOMONTH(date, [offset])`	Last day of month	2012+
`DATETRUNC(part, date)`	Truncate to precision	2022+
`DATE_BUCKET(part, n, date)`	Group into buckets	2022+
`AT TIME ZONE 'tz'`	Timezone conversion	2016+

Window Functions

Function	Description	Version
`ROW_NUMBER()`	Sequential unique numbers	2005+
`RANK()`	Rank with gaps for ties	2005+
`DENSE_RANK()`	Rank without gaps	2005+
`NTILE(n)`	Distribute into n groups	2005+
`LAG(col, n, default)`	Previous row value	2012+
`LEAD(col, n, default)`	Next row value	2012+
`FIRST_VALUE(col)`	First in window	2012+
`LAST_VALUE(col)`	Last in window	2012+
`IGNORE NULLS`	Skip NULLs in offset funcs	2022+

SQL Server 2022 New Functions

Function	Description
`GREATEST(v1, v2, ...)`	Maximum of values
`LEAST(v1, v2, ...)`	Minimum of values
`DATETRUNC(part, date)`	Truncate date
`GENERATE_SERIES(start, stop, [step])`	Number sequence
`JSON_OBJECT('key': val)`	Create JSON object
`JSON_ARRAY(v1, v2, ...)`	Create JSON array
`JSON_PATH_EXISTS(json, path)`	Check path exists
`IS [NOT] DISTINCT FROM`	NULL-safe comparison

Core Patterns

String Manipulation

-- Concatenate with separator (NULL-safe)
SELECT CONCAT_WS(', ', FirstName, MiddleName, LastName) AS FullName

-- Split string to rows with ordinal
SELECT value, ordinal
FROM STRING_SPLIT('apple,banana,cherry', ',', 1)

-- Aggregate strings with ordering
SELECT DeptID,
       STRING_AGG(EmployeeName, ', ') WITHIN GROUP (ORDER BY HireDate)
FROM Employees
GROUP BY DeptID

Date Operations

-- Truncate to first of month
SELECT DATETRUNC(month, OrderDate) AS MonthStart

-- Group by week buckets
SELECT DATE_BUCKET(week, 1, OrderDate) AS WeekBucket,
       COUNT(*) AS OrderCount
FROM Orders
GROUP BY DATE_BUCKET(week, 1, OrderDate)

-- Generate date series
SELECT CAST(value AS date) AS Date
FROM GENERATE_SERIES(
    CAST('2024-01-01' AS date),
    CAST('2024-12-31' AS date),
    1
)

Window Functions

-- Running total with partitioning
SELECT OrderID, CustomerID, Amount,
       SUM(Amount) OVER (
           PARTITION BY CustomerID
           ORDER BY OrderDate
           ROWS UNBOUNDED PRECEDING
       ) AS RunningTotal
FROM Orders

-- Get previous non-NULL value (SQL 2022+)
SELECT Date, Value,
       LAST_VALUE(Value) IGNORE NULLS OVER (
           ORDER BY Date
           ROWS BETWEEN UNBOUNDED PRECEDING AND 1 PRECEDING
       ) AS PreviousNonNull
FROM Measurements

JSON Operations

-- Extract scalar value
SELECT JSON_VALUE(JsonColumn, '$.customer.name') AS CustomerName

-- Parse JSON array to rows
SELECT j.ProductID, j.Quantity
FROM Orders
CROSS APPLY OPENJSON(OrderDetails)
WITH (
    ProductID INT '$.productId',
    Quantity INT '$.qty'
) AS j

-- Build JSON object (SQL 2022+)
SELECT JSON_OBJECT('id': CustomerID, 'name': CustomerName) AS CustomerJson
FROM Customers

Additional References

For deeper coverage of specific function categories, see:

references/string-functions.md - Complete string function reference with examples
references/window-functions.md - Window and ranking functions with frame specifications

FAQ

What does the tsql-functions skill do?

How do I install tsql-functions?

Run npx skills add https://github.com/josiahsiegel/claude-plugin-marketplace --skill tsql-functions in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/tsql-functions/ (personal) or .claude/skills/tsql-functions/ (project).

Which AI agents can use tsql-functions?

Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.

Is tsql-functions safe to install?

No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.

Who maintains tsql-functions?

It is published by josiahsiegel in josiahsiegel/claude-plugin-marketplace. It has 181 recorded installs.