Access VBA: Error when declaring the type of a Database object: User defined type is not defined

Question

In Access 2010 VBA, if I run this sub:

sub test

    Dim db
    Dim rst

    Set db = CurrentDb()
    Set rst = db.OpenRecordset("select * from mytable")

    Debug.Print "db:  " & TypeName(db)
    Debug.Print "rst: " & TypeName(rst)

end sub

then it shows (in the "Inmediate" panel):

db:  Database
rst: Recordset2

so it works, and all libraries are installed correctly (ADO for example).

Ok, now I want to declare explicitly the variable types, by using the types that were shown ("Database" and "Recordset2"), so I modify the sub in this way:

sub test

    Dim db   as Database        ' explicitly
    Dim rst  as Recordset2      ' explicitly

    Set db = CurrentDb()
    Set rst = db.OpenRecordset("select * from mytable")

    Debug.Print "db:  " & TypeName(db)
    Debug.Print "rst: " & TypeName(rst)

end sub

and when I run it, I get the following error at line "Dim db as Database":

Compilation error:
User defined type is not defined

So I understand that type "Database" is not defined (!). Why?

Note: I have also tried:

Dim db   as ADO.Database        ' explicitly
Dim rst  as ADO.Recordset2      ' explicitly

and:

Dim db   as ADODB.Database      ' explicitly
Dim rst  as ADODB.Recordset2    ' explicitly

and:

Dim db   as DAO.Database        ' explicitly
Dim rst  as DAO.Recordset2      ' explicitly

and got same error with all of them. How is it possible? Why does it work if I don't declare the type?

---

Edit: I have just discovered that Access also offers an ADODB.Connection object for the current database, by calling to "CurrentProject.Connection". So I can explicitly declare:

sub test

    Dim db As ADODB.Connection
    Set db = CurrentProject.Connection      ' Access gives an ADODB object too!

    Dim rst As ADODB.Recordset
    Set rst = New ADODB.Recordset
    rst.Open "select * from mytable", db

    Debug.Print "db:  " & TypeName(db)
    Debug.Print "rst: " & TypeName(rst)

end sub

that shows:

db:  Connection
rst: Recordset

So I will use it, since ADO is more modern than DAO.

Answer 1

Try to check "References" - you will see there is no DAO library. Your first example works because db has Variant type. And assignment

Set db = CurrentDb() 

puts COM object DAO.Database in db, and later TypeName confirms this is Database. If you want to use

Dim db   as DAO.Database 

You have to Reference appropriate library (Microsoft DAO for example)

Update by @John Shaw : now you can use library 'Microsoft Office 1X.0 Access database engine Object Library' as fully compaible replacement for 'Microsoft DAO'.