/ 
DBD-ADO-2.92
River stage one • 1 direct dependent • 1 total dependent
/ DBD::ADO

NAME

DBD::ADO - A DBI driver for Microsoft ADO (Active Data Objects)

SYNOPSIS

use DBI();

my $dbh = DBI->connect("dbi:ADO:$dsn", $usr, $pwd, $att ) or die $DBI::errstr;

DESCRIPTION

The DBD::ADO module supports ADO access on a Win32 machine. DBD::ADO is written to support the standard DBI interface to data sources.

PREREQUISITES

It is recommended that you use recent versions of the following prerequisites:

DBI
http://search.cpan.org/~timb/DBI/
Win32::OLE
http://search.cpan.org/~jdb/Win32-OLE/
ADO
http://msdn.microsoft.com/data/

Connection

Use the DBI connect method to establish a database connection:

my $dbh = DBI->connect("dbi:ADO:$dsn", $usr, $pwd, $att ) or die $DBI::errstr;

where

$dsn - is an ADO ConnectionString
$usr - is a user name
$pwd - is a password
$att - is a hash reference with additional attributes

Typical connection attributes are

RaiseError => 1
PrintError => 0
AutoCommit => 0

See the DBI module documentation for full details.

An ADO ConnectionString usually contains either a 'Provider' or a 'File Name' argument. If you omit these arguments, Provider defaults to MSDASQL (Microsoft OLE DB Provider for ODBC). Therefore you can pass an ODBC connection string (with DSN or DSN-less) as valid ADO connection string. If you use the OLE DB Provider for ODBC, it may be better to omit this additional layer and use DBD::ODBC with the ODBC driver.

In addition the following attributes may be set in the connection string:

Attributes
CommandTimeout
ConnectionString
ConnectionTimeout
CursorLocation
DefaultDatabase
IsolationLevel
Mode

Warning: The application is responsible for passing the correct information when setting any of these attributes.

See the ADO documentation for more information on connection strings.

ADO ConnectionString examples:

test
File Name=test.udl
Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\data\test.mdb
Provider=VFPOLEDB;Data Source=C:\data\test.dbc
Provider=MSDAORA

For more examples, see e.g.:

http://www.able-consulting.com/tech.htm

ADO-specific methods

ado_open_schema

$sth = $dbh->ado_open_schema( $QueryType, @Criteria ) or die ...;

This method can be used to obtain database schema information from the provider. It returns a valid statement handle upon success.

$QueryType may be any valid ADO SchemaEnum name such as

adSchemaTables
adSchemaIndexes
adSchemaProviderTypes

@Criteria (optional) is a list of query constraints depending on each $QueryType.

Example:

my $sth = $dbh->ado_open_schema('adSchemaCheckConstraints','Catalog1');

Note: With DBI version 1.36 and earlier, the func() method has to be used to call private methods implemented by the driver:

$h->func( @func_arguments, $func_name ) or die ...;

where $func_name is 'ado_open_schema'. You can use 'OpenSchema' for backward compatibility.

Example:

my $sth = $dbh->func('adSchemaCheckConstraints','Catalog1','OpenSchema');

See ex/OpenSchema.pl for a working example.

DBI Methods

data_sources

Because ADO doesn't provide a data source repository, DBD::ADO uses it's own. It tries to load Local::DBD::ADO::DSN and expects an array of hashes describing the data sources. See ex/Local/DBD/ADO/DSN.pm for an example.

Warning: This is experimental and may change.

Warning: Check for the unlikly case that a file Local/DBD/ADO/DSN.pm exists in your module search path which causes unwanted side effects when loaded.

prepare

The prepare methods allows attributes (see DBI):

$sth = $dbh->prepare( $statement )          or die $dbh->errstr;
$sth = $dbh->prepare( $statement, \%attr )  or die $dbh->errstr;

DBD::ADO's prepare() supports setting the CursorType, e.g.:

$sth = $dbh->prepare( $statement, { CursorType => 'adOpenForwardOnly' } ) ...

Possible cursortypes are:

adOpenForwardOnly (default)
adOpenKeyset
adOpenDynamic
adOpenStatic

It may be necessary to prepare the statement using cursortype 'adOpenStatic' when using a statement handle within a statement handle:

while( my $table = $sth1->fetchrow_hashref ) {
  ...
  my $col = $sth2->fetchrow_hashref;
  ...
}

Changing the CursorType is a solution to the following problem:

Can't execute statement 'select * from authors':
Lasterror : -2147467259
OLE exception from "Microsoft OLE DB Provider for SQL Server":

Cannot create new connection because in manual or distributed transaction
mode.

Win32::OLE(0.1403) error 0x80004005: "Unspecified error"
    in METHOD/PROPERTYGET "Open"

        Description : Cannot create new connection because in manual or distributed transaction mode.
        HelpContext : 0
        HelpFile    :
        NativeError : 0
        Number      : -2147467259
        Source      : Microsoft OLE DB Provider for SQL Server
        SQLState    :

bind_param

Normally, the datatypes of placeholders are known after the statement is prepared. In this case, you don't need to provide any type information:

$sth->bind_param( 1, $value );

Sometimes, you need to specify a type for the parameter, e.g.:

$sth->bind_param( 1, $value, SQL_NUMERIC );

As a last resort, you can provide an ADO-specific type, e.g.:

$sth->bind_param( 1, $value, { ado_type => 6 } );  # adCurrency

If no type is given (neither by the provider nor by you), the datatype defaults to SQL_VARCHAR (adVarChar).

Type info

There exists two implementations of type_info_all(). Which version is used depends on the ado_ti_ver database handle attribute:

$dbh->{ado_ti_ver} = 1

The first implementations tries to find for various DBI types a set of ADO types supported by the provider. The algorithm is highly sophisticated. It tends to generate more duplicate type codes and names.

$dbh->{ado_ti_ver} = 2 (default)

The second implementations is quite straightforward. It uses the set which the provider returns and tries to map various ADO codes to DBI/ODBC codes. The mapping is similar to the one used in column_info(). Duplicate type codes and names tend to occur less often. The rows are ordered by DATA_TYPE, but not necessarily by 'how closely each type maps to the corresponding ODBC SQL data type'. This second sort criterion is difficult to achieve.

table_info

Warning: This method is experimental and may change or disappear.

$sth = $dbh->table_info(\%attr);

$sth = $dbh->table_info({
  TABLE_TYPE => 'VIEW',
  ADO_Columns => 1,
  Trim_Catalog => 0,
  Filter => q{TABLE_NAME LIKE 'C%'},
});

Returns an active statement handle that can be used to fetch information about tables and views that exist in the database. By default the handle contains the columns described in the DBI documentation:

TABLE_CAT, TABLE_SCHEM, TABLE_NAME, TABLE_TYPE, REMARKS
ADO_Columns

Additional ADO-only fields will be included if the ADO_Columns attribute is set to true:

%attr = (ADO_Columns => 1);
Trim_Catalog

Some ADO providers include path info in the TABLE_CAT column. This information will be trimmed if the Trim_Catalog attribute is set to true:

%attr = (Trim_Catalog => 1);
Criteria

The ADO driver allows column criteria to be specified. In this way the record set can be restricted, for example, to only include tables of type 'VIEW':

%attr = (TABLE_TYPE => 'VIEW')

You can add criteria for any of the following columns:

TABLE_CAT, TABLE_SCHEM, TABLE_NAME, TABLE_TYPE
Filter

The ADO driver also allows the recordset to be filtered on a Criteria string: a string made up of one or more individual clauses concatenated with AND or OR operators.

%attr = (Filter => q{TABLE_TYPE LIKE 'SYSTEM%'})

The criteria string is made up of clauses in the form FieldName-Operator-Value. This is more flexible than using column criteria in that the filter allows a number of operators:

<, >, <=, >=, <>, =, or LIKE

The Fieldname must be one of the ADO 'TABLES Rowset' column names:

TABLE_CATALOG, TABLE_SCHEMA, TABLE_NAME, TABLE_TYPE, DESCRIPTION,
TABLE_GUID, TABLE_PROPID, DATE_CREATED, DATE_MODIFIED

Value is the value with which you will compare the field values (for example,'Smith', #8/24/95#, 12.345, or $50.00). Use single quotes with strings and pound signs (#) with dates. For numbers, you can use decimal points, dollar signs, and scientific notation. If Operator is LIKE, Value can use wildcards. Only the asterisk (*) and percent sign (%) wild cards are allowed, and they must be the last character in the string. Value cannot be null.

tables

Warning: This method is experimental and may change or disappear.

@names = $dbh->tables(\%attr);

Returns a list of table and view names. Accepts any of the attributes described in the table_info method:

@names = $dbh->tables({ TABLE_TYPE => 'VIEW' });

ADO specific attributes

ado_commandtimeout (all handles, decimal, inherited)

This attribute indicates the time (in seconds) after which a command is canceled. Typically, cancellation may occur during a long running execute method. Not all ADO providers support this functionality. Whereas ADO's Command object doesn't inherit the Connection's CommandTimeout setting, DBD::ADO's statement handle is initialized with the ado_commandtimeout attribute of its associated database handle.

Error handling

An ADO provider may return a collection of more than one error. After stringification , DBD::ADO concatenates these error messages to set the errstr value of the handle. However, the err value is set to the LastError known to Win32::OLE. Usually, this is the native OLE DB error code. These codes contain the following severity codes (see oledberr.h from the MDAC SDK):

00 - Success
01 - Informational
10 - Warning
11 - Error

The err value is set to 0 if all error codes belong to the Success or Informational category, which doesn't trigger the normal DBI error handling mechanisms.

The standard SQLSTATE is seldom supported by ADO providers and cannot be relied on.

The db/st handle attribute 'ado_max_errors' limits the number of errors extracted from the errors collection. To avoid time-consuming processing of huge error collections, it defaults to 50.

LOB support

Since version 2.92, DBD::ADO supports the DBI handle attributes LongReadLen and LongTruncOk. LongReadLen defaults to 2147483647 (for backwards compatibility).

For multibyte strings, it's unspecified whether LongReadLen means bytes or characters. It's passed through to ADO's GetChunk method and ActualSize property.

Caveat: Unexpected truncation errors may occur if the ADO provider (e.g. Microsoft.Jet.OLEDB.4.0) uses bytes for ActualSize but characters for GetChunk.

Caveat: The ADO provider may have problems if the long field isn't the last one in the list of selected columns, e.g.:

Description : Catastrophic failure
HelpContext : 5000000
   HelpFile :
NativeError :
     Number : -2147418113
     Source : Microsoft JET Database Engine
   SQLState :

The (experimental) blob_read method ignores the $offset argument for long fields (ADO maintains a current offset internally). To ensure that blob_read reads from the beginning, LongReadLen must be set to 0.

CAVEATS

Character set

Proper Unicode support depends on all components involved in your application: the DBMS, the ADO provider, Perl and some perl modules.

In short: Perl 5.8 and Win32::OLE 0.16 (or later) are strongly recommended and Win32::OLE has to be prepared to use the correct codepage:

Win32::OLE->Option( CP => Win32::OLE::CP_UTF8 );

More detailed notes can be found at

http://purl.net/stefan_ram/pub/perl_unicode_en

AUTHORS

Tim Bunce and Phlip. With many thanks to Jan Dubois and Jochen Wiedmann for additions, debuggery and general help. Special thanks to Thomas Lowery, who maintained this module 2001-2003. Current maintainer is Steffen Goeldner.

SUPPORT

This software is supported via the dbi-users mailing list. For more information and to keep informed about progress you can join the mailing list by sending a message to dbi-users-help@perl.org

Please post details of any problems (or changes you needed to make) to dbi-users@perl.org and CC them to me (sgoeldner@cpan.org).

COPYRIGHT

Copyright (c) 1998, Tim Bunce
Copyright (c) 1999, Tim Bunce, Phlip, Thomas Lowery
Copyright (c) 2000, Tim Bunce, Thomas Lowery
Copyright (c) 2001, Tim Bunce, Thomas Lowery, Steffen Goeldner
Copyright (c) 2002, Thomas Lowery, Steffen Goeldner
Copyright (c) 2003, Thomas Lowery, Steffen Goeldner
Copyright (c) 2004, Steffen Goeldner

All rights reserved.

You may distribute under the terms of either the GNU General Public
License or the Artistic License, as specified in the Perl README file.

SEE ALSO

Books

ADO Reference book:  ADO 2.0 Programmer's Reference
David Sussman and Alex Homer
Wrox
ISBN 1-861001-83-5

ADO: ActiveX Data Objects
Jason T. Roff
O'Reilly
ISBN 1-56592-415-0
http://www.oreilly.com/catalog/ado/index.html

If there's anything better please let me know.

Perl modules

DBI, DBD::ODBC, Win32::OLE