ADO Overview
ADO is a nice way to talk to your AS/400 as
it is a very high level object model that is easy to use. ADO
abstracts the programmer from the OLE DB interface. You
communicate with the AS/400 via an OLE DB provider. This
provider can the the Client Access Express OLE DB Provider, the
OLE DB Provider from Hit Software or you can use an ODBC
provider for the connection via the Microsoft MSDASQL Provider
which is an OLE DB provider for ODBC.
You can use ADO from a language like Visual
Basic or within Active Server Pages. You can also use ADO in any
of the Microsoft scripting languages like JavaScript or
VBScript. You can write macros in Word, Excel or PowerPoint to
allow these products to interact with data on your AS/400 via
ADO.
ADO consists of several high level objects:
Connection, Command and Recordset being the most important. A
Connection object is used to establish communications with the
AS/400. A command object is used to execute stored procedures or
prepared SQL statements. A Recordset object is used to iterate
through results of SQL statements or stored procedures.
Connecting to the AS/400
The following sample code connects to the AS/400
and retrieves a list of libraries into a recordset. This is VB
Code, so it would have to be executed in Word, Excel or the
Visual Basic environment in order to function. In addition,
Microsoft ActiveX Data Objects would have to be referenced in
the VB Project.
Dim Con1 As New
ADODB.Connection
Dim Cmd1 As New ADODB.Command
Dim RS As New ADODB.Recordset
Con1.Open "DSN=MY400;UID=HOWARD;PWD=SECRET;"
Cmd1.ActiveConnection = Con1
Cmd1.CommandText = "select distinct system_table_schema from
qsys2.systables"
RS.CacheSize = 200
RS.Open Cmd1
In the above example, RS would be
instantiated as a recordset object containing the results of the
select statement executed against the Cmd1 object.
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