What follows are two example procedures. The first,
CreateJetDB, creates a new Microsoft Jet database in the root directory of
drive C and populates it with data. The second, CursorLocationTimed,
demonstrates using the
Find method with a server side cursor and with a client side cursor.
To create these procedures, follow these steps:
- Create a new Microsoft Access database.
- Create a new module.
- On the Tools menu, click References, and make sure the following references are selected:
Microsoft ActiveX Data Objects 2.1 Library
Microsoft ADO Ext. 2.1 for DDL and Security
- Type the following procedures:
Sub CreateJetDB()
Dim cat As ADOX.Catalog
Dim cn As ADODB.Connection
Dim rs As ADODB.Recordset
Dim numrecords As Long
Dim i As Long
Set cat = New ADOX.Catalog
Set cn = New ADODB.Connection
Set rs = New ADODB.Recordset
' Number of sample records to create
numrecords = 250000
On Error Resume Next
'Delete the sample database if it already exists.
Kill "c:\findseek.mdb"
On Error GoTo 0
' Create a new Jet 4.0 database name findseek.mdb
cat.Create "Provider=Microsoft.Jet.OLEDB.4.0;" & _
"Data Source=c:\findseek.mdb"
' Set the provider, open the database,
'and create a new table called tblSequential.
cn.Provider = "Microsoft.Jet.OLEDB.4.0"
cn.Open "Data Source=c:\findseek.mdb"
cn.Execute "CREATE TABLE tblSequential (col1 long, col2 text(75));"
'Open the new table.
rs.Open "tblSequential", cn, adOpenDynamic, _
adLockOptimistic, adCmdTableDirect
' Add sample records to the tblSequential table.
For i = 0 To numrecords
rs.AddNew
rs.Fields("col1").Value = i
rs.Fields("col2").Value = "value_" & i
rs.Update
Next i
rs.Close
'Create a multifield Index on col1 and col2.
cn.Execute "CREATE INDEX idxSeqInt on tblSequential (col1, col2);"
'Close the connection
cn.Close
End Sub
Sub CursorLocationTimed()
Dim cn As ADODB.Connection
Dim rs As ADODB.Recordset
Dim i, j As Long
Dim time As Variant
Set cn = New ADODB.Connection
Set rs = New ADODB.Recordset
On Error GoTo ErrHandler
cn.Open "Provider=Microsoft.Jet.OLEDB.4.0;" _
& "Data Source=c:\findseek.mdb"
' Specify how ADO should open the recordset:
' adUseServer - use the native provider to perform cursor
' operations
' adUseClient - use the client cursor engine in ADO
' NOTE: adUseServer more closely resembles DAO
' Time opening a recordset and doing 1000 finds (Server cursor
' engine)
'
rs.CursorLocation = adUseServer
time = Timer
' Open the recordset and perform serveral Finds to locate records.
' Using the adCmdTableDirect opens a base table against Jet, which
' is generally the fastest, most functional way to access tables.
rs.Open "tblSequential", cn, adOpenDynamic, adLockOptimistic, _
adCmdTableDirect
For i = 0 To 1000
rs.Find "col1=" & i
Next i
Debug.Print "Sequential Find + Open (Server) = " & Timer - time
rs.Close
' Time opening a recordset and doing 1000 finds (Client cursor
' engine)
rs.CursorLocation = adUseClient
time = Timer
rs.Open "tblSequential", cn, adOpenDynamic, _
adLockOptimistic, adCmdTableDirect
For i = 0 To 1000
rs.Find "col1=" & i
Next i
Debug.Print "Sequential Find + Open (Client) = " & Timer - time
rs.Close
Exit Sub
ErrHandler:
For j = 0 To cn.Errors.Count - 1
Debug.Print "Conn Err Num : "; cn.Errors(j).Number
Debug.Print "Conn Err Desc: "; cn.Errors(j).Description
Next j
Resume Next
End Sub
- To create the sample database, type the following line in
the Immediate window, and then press ENTER:
- To demonstrate the Find method, type the following line in the Immediate window, and then
press ENTER: You should next see output similar to the following:
Sequential Find + Open (Server) = 0.28125
Sequential Find + Open (Client) = 5.28125
NOTE: The resulting numbers may differ from computer to
computer.