feat(sqlserver): surface informational messages (STATISTICS, PRINT) in query results

[esetnik]

Summary

SQL Server emits informational messages via the TDS protocol for SET STATISTICS TIME/IO output, PRINT statements, and warnings. The mssql driver's Request object exposes these through info events, but they were previously discarded.

This change captures those messages during query execution and includes them in the response when present, enabling MCP clients to access query performance statistics and diagnostic output.

Motivation

When using DBHub as an MCP server to analyze SQL Server query performance, there's currently no way to see SET STATISTICS TIME ON or SET STATISTICS IO ON output — the tool only returns result set rows. This forces users to work around the limitation with DECLARE @start timing variables or DMV queries, which provide less detail than the native statistics output.

With this change, running:

SET STATISTICS TIME ON;
SELECT TOP 10 * FROM users;
SET STATISTICS TIME OFF;

...will include the CPU/elapsed time breakdown in the response's messages array alongside the result rows.

Changes

• src/connectors/interface.ts: Add optional messages?: string[] field to SQLResult
• src/connectors/sqlserver/index.ts: Listen for info events on the Request object before executing queries, collect messages, and include them in the result when present
• src/tools/execute-sql.ts: Pass messages through to the MCP tool response when non-empty

Notes

• The change is backward-compatible — messages is optional and only included when non-empty
• Only the SQL Server connector is affected; other connectors continue to return the same SQLResult shape
• The mssql package's Request.on('info') event covers all SQL Server informational messages (severity < 10): statistics, print output, warnings, etc.

[Copilot]

Pull request overview

This PR adds support for surfacing SQL Server informational messages (e.g., SET STATISTICS TIME/IO, PRINT, warnings) by capturing mssql Request info events during execution and returning them to MCP clients when present.

Changes:

• Extend SQLResult with an optional messages?: string[] field for informational DB messages.
• Capture SQL Server Request info events during query execution and include them in the connector result.
• Pass messages through the execute_sql tool response when non-empty.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/connectors/interface.ts	Adds optional messages to the shared SQLResult contract.
src/connectors/sqlserver/index.ts	Collects SQL Server informational messages via Request.on('info') and returns them in SQLResult.
src/tools/execute-sql.ts	Includes messages in the tool response payload when provided by the connector.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

[Copilot]

rowCount is derived from result.rowsAffected[0], which is incorrect for multi-statement batches (e.g. SET STATISTICS TIME ON; SELECT ...; SET STATISTICS TIME OFF; or PRINT ...; SELECT ...;). In those cases the first statement often affects 0 rows, so count will be reported as 0 even when recordset contains rows. Consider computing rowCount based on the returned recordset (for SELECT) and/or using the last entry in rowsAffected (or summing it) to reflect the statement(s) that actually produced the returned rows.

Suggested change

	return {
	rows: result.recordset || [],
	rowCount: result.rowsAffected[0] || 0,
	const rows = result.recordset || [];
	const rowCount = rows.length > 0
	? rows.length
	: (result.rowsAffected && result.rowsAffected.length > 0
	? result.rowsAffected[result.rowsAffected.length - 1] || 0
	: 0);
	return {
	rows,
	rowCount,