How to extract the schema of an Access (.mdb) database?

Question

I am trying to extract the schema of an .mdb database, so that I can recreate the database elsewhere.

How can I pull off something like this?

Answer 1

It's an ancient question now, but unfortunately perennial :(

I thought this code may be of use to others looking for solutions. It's designed to be run from the command line via cscript, so no need to import code into your Access project. Similar to (and inspired by) the code from Oliver in How do you use version control with Access development.

' Usage:
'  CScript //Nologo ddl.vbs  > 

'
' Outputs DDL statements for tables, indexes, and relations from Access file 
' (.mdb, .accdb)  to stdout.  
' Requires Microsoft Access.
'
' NOTE: Adapted from code from "polite person" + Kevin Chambers - see:
' http://www.mombu.com/microsoft/comp-databases-ms-access/t-exporting-jet-table-metadata-as-text-119667.html
'
Option Explicit
Dim stdout, fso
Dim strFile
Dim appAccess, db, tbl, idx, rel

Set stdout = WScript.StdOut
Set fso = CreateObject("Scripting.FileSystemObject")

' Parse args
If (WScript.Arguments.Count = 0) then
    MsgBox "Usage: cscript //Nologo ddl.vbs access-file", vbExclamation, "Error"
    Wscript.Quit()
End if
strFile = fso.GetAbsolutePathName(WScript.Arguments(0))

' Open mdb file
Set appAccess = CreateObject("Access.Application")
appAccess.OpenCurrentDatabase strFile
Set db = appAccess.DBEngine(0)(0)

' Iterate over tables
  ' create table statements
For Each tbl In db.TableDefs
  If Not isSystemTable(tbl) And Not isHiddenTable(tbl) Then
    stdout.WriteLine getTableDDL(tbl)
    stdout.WriteBlankLines(1)

    ' Iterate over indexes
      ' create index statements
    For Each idx In tbl.Indexes
      stdout.WriteLine getIndexDDL(tbl, idx)
    Next

    stdout.WriteBlankLines(2)
  End If
Next

' Iterate over relations
  ' alter table add constraint statements
For Each rel In db.Relations
  Set tbl = db.TableDefs(rel.Table)
  If Not isSystemTable(tbl) And Not isHiddenTable(tbl) Then
    stdout.WriteLine getRelationDDL(rel)
    stdout.WriteBlankLines(1)
  End If
Next

Function getTableDDL(tdef)
Const dbBoolean = 1
Const dbByte = 2
Const dbCurrency = 5
Const dbDate = 8
Const dbDouble = 7
Const dbInteger = 3
Const dbLong = 4
Const dbDecimal = 20
Const dbFloat = 17
Const dbMemo = 12
Const dbSingle = 6
Const dbText = 10
Const dbGUID = 15
Const dbAutoIncrField = 16

Dim fld
Dim sql
Dim ln, a

    sql = "CREATE TABLE " & QuoteObjectName(tdef.name) & " ("
    ln = vbCrLf

    For Each fld In tdef.fields
       sql = sql & ln & " " & QuoteObjectName(fld.name) & " "
       Select Case fld.Type
       Case dbBoolean   'Boolean
          a = "BIT"
       Case dbByte   'Byte
          a = "BYTE"
       Case dbCurrency  'Currency
          a = "MONEY"
       Case dbDate 'Date / Time
          a = "DATETIME"
       Case dbDouble    'Double
          a = "DOUBLE"
       Case dbInteger   'Integer
          a = "INTEGER"
       Case dbLong  'Long
          'test if counter, doesn't detect random property if set
          If (fld.Attributes And dbAutoIncrField) Then
             a = "COUNTER"
          Else
             a = "LONG"
          End If
       Case dbDecimal    'Decimal
          a = "DECIMAL"
       Case dbFloat      'Float
          a = "FLOAT"
       Case dbMemo 'Memo
          a = "MEMO"
       Case dbSingle    'Single
          a = "SINGLE"
       Case dbText 'Text
          a = "VARCHAR(" & fld.Size & ")"
       Case dbGUID 'Text
          a = "GUID"
       Case Else
          '>>> raise error
          MsgBox "Field " & tdef.name & "." & fld.name & _
                " of type " & fld.Type & " has been ignored!!!"
       End Select

       sql = sql & a

       If fld.Required Then _
          sql = sql & " NOT NULL "
       If Len(fld.DefaultValue) > 0 Then _
          sql = sql & " DEFAULT " & fld.DefaultValue

       ln = ", " & vbCrLf
    Next

    sql = sql & vbCrLf & ");"
    getTableDDL = sql

End Function

Function getIndexDDL(tdef, idx)
Dim sql, ln, myfld

    If Left(idx.name, 1) = "{" Then
       'ignore, GUID-type indexes - bugger them
    ElseIf idx.Foreign Then
       'this index was created by a relation.  recreating the
       'relation will create this for us, so no need to do it here
    Else
       ln = ""
       sql = "CREATE "
       If idx.Unique Then
           sql = sql & "UNIQUE "
       End If
       sql = sql & "INDEX " & QuoteObjectName(idx.name) & " ON " & _
             QuoteObjectName(tdef.name) & "( "
       For Each myfld In idx.fields
          sql = sql & ln & QuoteObjectName(myfld.name)
          ln = ", "
       Next
       sql = sql & " )"
       If idx.Primary Then
          sql = sql & " WITH PRIMARY"
       ElseIf idx.IgnoreNulls Then
          sql = sql & " WITH IGNORE NULL"
       ElseIf idx.Required Then
          sql = sql & " WITH DISALLOW NULL"
       End If
       sql = sql & ";"
    End If
    getIndexDDL = sql

End Function

' Returns the SQL DDL to add a relation between two tables.
' Oddly, DAO will not accept the ON DELETE or ON UPDATE
' clauses, so the resulting sql must be executed through ADO
Function getRelationDDL(myrel)
Const dbRelationUpdateCascade = 256
Const dbRelationDeleteCascade = 4096
Dim mytdef
Dim myfld
Dim sql, ln


    With myrel
       sql = "ALTER TABLE " & QuoteObjectName(.ForeignTable) & _
             " ADD CONSTRAINT " & QuoteObjectName(.name) & " FOREIGN KEY ( "
       ln = ""
       For Each myfld In .fields 'ie fields of the relation
          sql = sql & ln & QuoteObjectName(myfld.ForeignName)
          ln = ","
       Next
       sql = sql & " ) " & "REFERENCES " & _
             QuoteObjectName(.table) & "( "
       ln = ""
       For Each myfld In .fields
          sql = sql & ln & QuoteObjectName(myfld.name)
          ln = ","
       Next
       sql = sql & " )"
       If (myrel.Attributes And dbRelationUpdateCascade) Then _
             sql = sql & " ON UPDATE CASCADE"
       If (myrel.Attributes And dbRelationDeleteCascade) Then _
             sql = sql & " ON DELETE CASCADE"
       sql = sql & ";"
    End With
    getRelationDDL = sql
End Function


Function isSystemTable(tbl)
Dim nAttrib
Const dbSystemObject = -2147483646
    isSystemTable = False
    nAttrib = tbl.Attributes
    isSystemTable = (nAttrib <> 0 And ((nAttrib And dbSystemObject) <> 0))
End Function

Function isHiddenTable(tbl)
Dim nAttrib
Const dbHiddenObject = 1
    isHiddenTable = False
    nAttrib = tbl.Attributes
    isHiddenTable = (nAttrib <> 0 And ((nAttrib And dbHiddenObject) <> 0))
End Function

Function QuoteObjectName(str)
    QuoteObjectName = "[" & str & "]"
End Function

If you are looking to export query definitions as well, this question should help. It's a little different because you don't usually create querydefs with plain DDL CREATE VIEW foo AS ... syntax, in fact I'm not sure you can (?)

But here's a little piece of a script I wrote for backing up queries to separate .sql files (which is part of a larger script for backing up all front-end db code, see Oliver's answer for this question).

Dim oApplication
Set oApplication = CreateObject("Access.Application")
oApplication.OpenCurrentDatabase sMyAccessFilePath
oApplication.Visible = False

For Each myObj In oApplication.DBEngine(0)(0).QueryDefs
    writeToFile sExportpath & "\queries\" & myObj.Name & ".sql", myObj.SQL 
Next

Function writeToFile(path, text)
Dim fso, st
  Set fso = CreateObject("Scripting.FileSystemObject")
  Set st = fso.CreateTextFile(path, True)
  st.Write text
  st.Close
End Function