if you want sp_executesql with variables.

openquery do not allow any var's.

CREATE function [dbo].[create_SQL_string](@driver nvarchar(32), @sql nvarchar(max))

returns nvarchar(max)

with execute as caller

as begin

declare @out_sql nvarchar(max)

return 'select * from openquery('+@driver+', '''+REPLACE(@sql,'''','''''')+''')'

end

declare @a nvarchar(512)

set @a = (select [dbo].[create_SQL_string](N'SRV', @query))

exec sp_executesql @a