This is a stored procedure for SQL Server that formats the output of an SQL query as Markdown.

sp_Markdown.sql

USE master;
GO

/*
	2025-04-14 Lars Rönnbäck		CREATED
	2025-04-15 Lars Rönnbäck		Renamed to dbo.sp_Markdown.
						            Uses FOR XML AUTO and REPLACE to handle spaces in column names.
	2025-05-26 Lars Rönnbäck		Handle NULL values.
						            Detection of last element through local-name().

	TEST: 
	sp_Markdown 'SELECT * FROM master.sys.schemas'

*/
CREATE OR ALTER PROC dbo.sp_Markdown (
	@SQL VARCHAR(MAX), 
	@null VARCHAR(555) = 'NULL'
)
AS
BEGIN

-- FOR XML AUTO converts spaces to _x0020_ since they are not allowed in XML tags.
-- If other characters are converted the REPLACE below may need to be extended.
SET @SQL = '
SELECT REPLACE(R.value(''.'', ''varchar(max)''), ''_x0020_'', '' '') AS [Markdown]
FROM (
	SELECT (
		SELECT *
		FROM ( ' + @SQL + ') s
		FOR XML AUTO, ELEMENTS XSINIL, TYPE
	).query(''
		for $r in *[1]
			let $last := $r/*[last()]
			return <R>{
			for $x in $r/*
				return 
					if (local-name($x) = local-name($last)) then
						concat("| ", local-name($x), " |")
					else 
						concat("| ", local-name($x))
			}</R>,
		for $r in *[1]
			let $last := $r/*[last()]
			return <R>{
			for $x in $r/*
				return 
					if (local-name($x) = local-name($last)) then
						"|-----|"
					else 
						"|-----"
			}</R>,
		for $r in *
			let $last := $r/*[last()]
			return <R>{
			for $x in $r/*
				return
					if (local-name($x) = local-name($last) and $x/@xsi:nil = "true") then
						"| ' + @null + ' |"
					else if (local-name($x) = local-name($last)) then
						concat("| ", string($x), " |")
					else if ($x/@xsi:nil = "true") then
						"| ' + @null + '"
					else
						concat("| ", string($x))
			}</R>
	'')
) X(V)
CROSS APPLY V.nodes(''R'') V(R)
';

EXEC(@SQL);

END