get `sp_attach_db` scripts for all databases

generate_attaches.sql

-- due to https://www.mssqltips.com/sqlservertip/1786/auto-generate-sql-server-database-attach-and-detach-scripts/
-- modified to use NVARCHAR for names

SET NOCOUNT ON 
DECLARE     @cmd        NVARCHAR(MAX),
            @dbname     NVARCHAR(200),
            @prevdbname NVARCHAR(200)

SELECT @cmd = N'', @dbname = N';', @prevdbname = N''

CREATE TABLE #Attach
    (Seq        INT IDENTITY(1,1) PRIMARY KEY,
     dbname     SYSNAME NULL,
     fileid     INT NULL,
     filename   NVARCHAR(1000) NULL,
     TxtAttach  NVARCHAR(MAX) NULL
)

-- find files names that begin with "F"
INSERT INTO #Attach
SELECT DISTINCT DB_NAME(dbid) AS dbname, fileid, filename, CONVERT(NVARCHAR(MAX),'') AS TxtAttach
FROM master.dbo.sysaltfiles
WHERE dbid IN (SELECT dbid FROM master.dbo.sysaltfiles 
            WHERE SUBSTRING(filename,1,1) IN ('F'))
            AND DATABASEPROPERTYEX( DB_NAME(dbid) , 'Status' ) = 'ONLINE'
            AND DB_NAME(dbid) NOT IN ('master','tempdb','msdb','model')
ORDER BY dbname, fileid, filename 


UPDATE #Attach
SET @cmd = TxtAttach =  
            CASE WHEN dbname <> @prevdbname 
            THEN CONVERT(NVARCHAR(200), N'exec sp_attach_db @dbname = N''' + dbname + N'''')
            ELSE @cmd
            END + N',@filename' + CONVERT(NVARCHAR(10),fileid) + '=N''' + filename + N'''',
    @prevdbname = CASE WHEN dbname <> @prevdbname THEN dbname ELSE @prevdbname END,
    @dbname = dbname
FROM #Attach 

SELECT TxtAttach
FROM
(SELECT dbname, MAX(TxtAttach) AS TxtAttach FROM #Attach 
 GROUP BY dbname) AS x

DROP TABLE #Attach
GO