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Microsoft KB Archive/106297

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INF: How to Find Which Groups a User Belongs To

PSS ID Number: Q106297 Article last modified on 10-04-1994

1.00 1.10

WINDOWS

The information in this article applies to:
- Microsoft Access versions 1.0 and 1.1

SUMMARY

Microsoft Access has no built-in mechanism for finding which groups a user belongs to. This article demonstrates a sample Access Basic function that you can use to check if a user is a member of a specific group.

Notes

  • The technique described below relies on the use of tables stored with your SYSTEM.MDA file. These tables are undocumented and are subject to change in future versions of Microsoft Access. Use of the system tables is not supported by Microsoft.
  • This article assumes that you are familiar with Access Basic and with creating Microsoft Access applications using the programming tools provided with Microsoft Access. For more information on Access Basic, please refer to the “Introduction to Programming” manual.

MORE INFORMATION

You can use the following sample function to check if a user belongs to a specific group:

NOTE: In the following sample code, an underscore (_) is used as a line- continuation character. Remove the underscore when re-creating this code in Access Basic.

‘————————————— ’GLOBAL DECLARATIONS SECTION’————————————— Option Explicit

‘————————————— ’Function: ug_Group()’————————————— Function ug_Group (UserName As String, CheckGroup As Variant) Dim MyDB As Database, MyQueryDef As QueryDef, MySnap As Snapshot

  'Trap Error
   On Error GoTo ug_Group_Err

  'Verify CheckGroup is String or Null
   If VarType(CheckGroup) <> 1 And VarType(CheckGroup) <> 8 Then
     ug_Group = Null
     Exit Function
   End If

   Set MyDB = OpenDatabase("SYSTEM.MDA")
   Set MyQueryDef = MyDB.OpenQueryDef("MSysUserMemberships")
   MyQueryDef![UserName] = UserName
   Set MySnap = MyQueryDef.CreateSnapshot()

   'Check if CheckGroup = Null or String
   If IsNull(CheckGroup) Then
       If MySnap.BOF Then
           ug_Group = 0
       Else
           MySnap.MoveLast
           ug_Group = MySnap.RecordCount
       End If
   Else
         MySnap.FindFirst "[Name]='" & CheckGroup & "'"
         ug_Group = IIf(MySnap.NoMatch, False, True)
   End If

   MySnap.Close
   MyQueryDef.Close
   MyDB.Close
   Exit Function

ug_Group_Err: ug_Group = “Error:” & Error Exit Function

End Function

You can use the function ug_Group() to check if a user belongs to a specific group, or to determine the total number of groups to which the user belongs. You can specify any user in the SYSTEM.MDA file, or you can dynamically determine the current user of the application.

The ug_Group() function uses the following arguments:

Argument Description
UserName String expression of the user to be
checked. Use the User() function to pass the
current user.

CheckGroup Variant expression of the group to check if UserName is a member. A group name is passed as a String expression. Optionally, this value can be passed as null.

If the argument CheckGroup is a String, the function will return true (-1) if the UserName is a member of CheckGroup, or will return false if the UserName is not a member of CheckGroup.

If the argument CheckGroup is null, the function will return the number of groups of which UserName is a member. If the UserName has not been defined as a user in the SYSTEM.MDA file, the value 0 will be returned. Since all users are members of the group Users, the function will return the value 1 if UserName is not a member of any other groups. The function will return a value greater than 1 if UserName is a member of other groups. The value returned will equal the total number of groups of which UserName is a member.

If the argument CheckGroup is not a String or null, the function will return null.

If an error occurs within the function, a description of the error will be returned.

For example, assume the following users and groups have been created:

Users: Donald, Jeanie, and Chelsea Groups: People and Pets

Donald is a member of the groups People and Users. Jeanie is a member of the groups People and Users. Chelsea is a member of the groups People, Pets, Users, and Admins.

Also assume that Chelsea is currently logged into Microsoft Access.

Type the following examples in an Immediate window and note the results. Remember that -1 equals true and 0 equals false:

Example: ? ug_Group( User(), “Admins” ) Response: -1 Meaning: Chelsea is a member of Admins.

Example: ? ug_Group( “Donald”, “Pets” ) Response: 0 Meaning: Donald is not a member of Pets.

Example: ? ug_Group( “Jeanie”, NULL) Response: 2 Meaning: Jeanie is a member of two groups.

REFERENCES

Microsoft Access “User’s Guide,” Chapter 25

Microsoft Access “Language Reference,” page 489

Additional reference words: 1.00 1.10 ADK KBCategory: kbusage KBSubcategory: ScrtOthr ============================================================================= Copyright Microsoft Corporation 1994.