ACC2000: Sample Code to Check for Table or Query in a Database

• Microsoft Access 2000

SUMMARY

This article contains a sample user-defined function named IsTableQuery() that you can use to determine whether a table or a query exists in a database. The sample function uses the TableDefs and QueryDefs Data Access Objects (DAO) collections.

MORE INFORMATION

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1. Open the sample database Northwind.mdb.



2. Create a module and type the following line in the Declarations section if it isn't already there:




Option Explicit 

3. Type the following procedure:




'********************************************************
' FUNCTION: IsTableQuery()
'
' PURPOSE: Determine if a table or query exists.
'
' ARGUMENTS:
'   DbName: The name of the database. If the database name
'           is "" the current database is used.
'    TName: The name of a table or query.
'
' RETURNS: True (it exists) or False (it does not exist).
'
'********************************************************

Function IsTableQuery(DbName As String, TName As String) As Integer

   Dim Db As DAO.Database, Found As Integer, Test As String
   Const NAME_NOT_IN_COLLECTION = 3265

   ' Assume the table or query does not exist.
   Found = False

   ' Trap for any errors.
   On Error Resume Next

   ' If the database name is empty...
   If Trim$(DbName) = "" Then
      ' ...then set Db to the current Db.
      Set Db = CurrentDb()
   Else
      ' Otherwise, set Db to the specified open database.
      Set Db = DBEngine.Workspaces(0).OpenDatabase(DbName)

      ' See if an error occurred.
      If Err Then
         MsgBox "Could not find database to open: " & DbName
         IsTableQuery = False
         Exit Function
      End If
   End If

   ' See if the name is in the Tables collection.
   Test = Db.TableDefs(TName).Name
   If Err <> NAME_NOT_IN_COLLECTION Then Found = True

   ' Reset the error variable.
   Err = 0

   ' See if the name is in the Queries collection.
   Test = Db.QueryDefs(TName$).Name
   If Err <> NAME_NOT_IN_COLLECTION Then Found = True

   Db.Close

   IsTableQuery = Found

End Function 

4. To test this function, type the following line in the Immediate window, and then press ENTER:

   
   ?IsTableQuery("","Invoices") 

   
   Note that a "-1" is displayed, indicating that the Invoices query was found (Microsoft Access stores a "-1" for True and a "0" for False).



5. Try using other valid database names and other table and query names in the line above.

REFERENCES

For more information about the TableDefs collection, in the Visual Basic Editor, click Microsoft Visual Basic Help on the Help menu, type "TableDefs collection" in the Office Assistant or the Answer Wizard, and then click Search to view the topic.

For more information about the QueryDefs collection, in the Visual Basic Editor, click Microsoft Visual Basic Help on the Help menu, type "QueryDefs collection" in the Office Assistant or the Answer Wizard, and then click Search to view the topic.

Additional query words: inf how to determine exists

Keywords : kbprg kbdta AccCon PgmObj
Version : WINDOWS:2000
Platform : WINDOWS
Issue type : kbhowto