Tim Bunce > DBD-ODBC-0.20 > DBD::ODBC

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Module Version: 0.20   Source   Latest Release: DBD-ODBC-1.51_2

NAME ^

DBD::ODBC - ODBC Driver for DBI

SYNOPSIS ^

  use DBI;

  $dbh = DBI->connect('dbi:ODBC:DSN', 'user', 'password');

See DBI for more information.

DESCRIPTION ^

Recent Updates

DBD::ODBC 0.20

SQLColAttributes fixes for SQL Server and MySQL. Fixed tables method by renaming to new table_info method. Added new tyoe_info_all method. Improved Makefile.PL support for Adabase.

DBD::ODBC 0.19

Added iODBC source code to distribution.Fall-back to using iODBC header files in some cases.

DBD::ODBC 0.18

Enhancements to build process. Better handling of errors in error handling code.

DBD::ODBC 0.17

This release is mostly due to the good work of Jeff Urlwin. My eternal thanks to you Jeff.

Fixed "SQLNumResultCols err" on joins and 'order by' with some drivers (see Microsoft Knowledge Base article #Q124899). Thanks to Paul O'Fallon for that one.

Added more (probably incomplete) support for unix ODBC in Makefile.PL

Increased default SQL_COLUMN_DISPLAY_SIZE and SQL_COLUMN_LENGTH to 2000 for drivers that don't provide a way to query them dynamically. Was 100!

When fetch reaches the end-of-data it automatically frees the internal ODBC statement handle and marks the DBI statement handle as inactive (thus an explicit 'finish' is *not* required).

Also:

  LongTruncOk for Oracle ODBC (where fbh->datalen < 0)
  Added tracing into SQLBindParameter (help diagnose oracle odbc bug)
  Fixed/worked around bug/result from Latest Oracle ODBC driver where in
     SQLColAttribute cbInfoValue was changed to 0 to indicate fDesc had a value
  Added work around for compiling w/ActiveState PRK (PERL_OBJECT)
  Updated tests to include date insert and type
  Added more "backup" SQL_xxx types for tests                                  
  Updated bind test to test binding select
  NOTE: bind insert fails on Paradox driver (don't know why)

Added support for: (see notes below)

  SQLGetInfo       via $dbh->func(xxx, GetInfo)
  SQLGetTypeInfo   via $dbh->func(xxx, GetTypeInfo)
  SQLDescribeCol   via $sth->func(colno, DescribeCol)
  SQLColAttributes via $sth->func(xxx, colno, ColAttributes)
  SQLGetFunctions  via $dbh->func(xxx, GetFunctions)
  SQLColumns       via $dbh->func(catalog, schema, table, column, 'columns')

Fixed $DBI::err to reflect the real ODBC error code which is a 5 char code, not necessarily numeric.

Fixed fetches when LongTruncOk == 1.

Updated tests to pass more often (hopefully 100% <G>)

Updated tests to test long reading, inserting and the LongTruncOk attribute.

Updated tests to be less driver specific.

They now rely upon SQLGetTypeInfo heavily in order to create the tables. The test use this function to "ask" the driver for the name of the SQL type to correctly create long, varchar, etc types. For example, in Oracle the SQL_VARCHAR type is VARCHAR2, while MS Access uses TEXT for the SQL Name. Again, in Oracle the SQL_LONGVARCHAR is LONG, while in Access it's MEMO. The tests currently handle this correctly (at least with Access and Oracle, MS SQL server will be tested also).

Private functions for ODBC API access

It is anticipated that at least some of the functions currently implemented via the func interface be "moved" into a more formal, DBI specification. This will be when the DBI specification supports/formalizes the meta-data to implement. Most of these functions are to obtain more information from the driver and the data source.

GetInfo

This function maps to the ODBC SQLGetInfo call. This is a Level 1 ODBC function. An example of this is:

  $value = $dbh->func(6, GetInfo);

This function returns a scalar value, which can be a numeric or string value. This depends upon the argument passed to GetInfo.

SQLGetTypeInfo

This function maps to the ODBC SQLGetTypeInfo call. This is a Level 1 ODBC function. An example of this is:

  use DBI qw(:sql_types);

  $sth = $dbh->func(SQL_ALL_TYPES, GetInfo);
  while (@row = $sth->fetch_row) {
    ...
  }

This function returns a DBI statement handle, which represents a result set containing type names which are compatible with the requested type. SQL_ALL_TYPES can be used for obtaining all the types the ODBC driver supports. NOTE: It is VERY important that the use DBI includes the qw(:sql_types) so that values like SQL_VARCHAR are correctly interpreted. This "imports" the sql type names into the program's name space. A very common mistake is to forget the qw(:sql_types) and obtain strange results.

GetFunctions

This function maps to the ODBC API SQLGetFunctions. This is a Level 1 API call which returns supported driver funtions. Depending upon how this is called, it will either return a 100 element array of true/false values or a single true false value. If it's called with SQL_API_ALL_FUNCTIONS (0), it will return the 100 element array. Otherwise, pass the number referring to the function. (See your ODBC docs for help with this).

SQLColumns

Support for this function has been added in version 0.17, however, it couldn't be tested properly using the ODBC drivers I have. Neither (Oracle or Access) supported this. I can tell you that it fails properly, though <G>

Others/todo?

Level 1

    SQLColumns  
    SQLSpecialColumns
    SQLStatistics
    SQLTables (use tables()) call

Level 2

    SQLColumnPrivileges
    SQLForeignKeys
    SQLPrimaryKeys
    SQLProcedureColumns
    SQLProcedures
    SQLTablePrivileges
    SQLDataSources
    SQLDrivers
    SQLNativeSql

Using DBD::ODBC with web servers under Win32.

General Commentary re web database access

This should be a DBI faq, actually, but this has somewhat of an Win32/ODBC twist to it.

Typically, the Web server is installed as an NT service or a Windows 95/98 service. This typically means that the web server itself does not have the same environment and permissions the web developer does. This situation, of course, can and does apply to Unix web servers. Under Win32, however, the problems are usually slightly different.

Defining your DSN -- which type should I use?

Under Win32 take care to define your DSN as a system DSN, not as a user DSN. The system DSN is a "global" one, while the user is local to a user. Typically, as stated above, the web server is "logged in" as a different user than the web developer. This helps cause the situation where someone asks why a script succeeds from the command line, but fails when called from the web server.

Defining your DSN -- careful selection of the file itself is important!

For file based drivers, rather than client server drivers, the file path is VERY important. There are a few things to keep in mind. This applies to, for example, MS Access databases.

1) If the file is on an NTFS partition, check to make sure that the Web service user has permissions to access that file.

2) If the file is on a remote computer, check to make sure the Web service user has permissions to access the file.

3) If the file is on a remote computer, try using a UNC path the file, rather than a X:\ notation. This can be VERY important as services don't quite get the same access permissions to the mapped drive letters and, more importantly, the drive letters themselves are GLOBAL to the machine. That means that if the service tries to access Z:, the Z: it gets can depend upon the user who is logged into the machine at the time. (I've tested this while I was developing a service -- it's ugly and worth avoiding at all costs).

Unfortunately, the Access ODBC driver that I have does not allow one to specify the UNC path, only the X:\ notation. There is at least one way around that. The simplest is probably to use Regedit and go to (assuming it's a system DSN, of course) HKEY_LOCAL_USERS\SOFTWARE\ODBC\"YOUR DSN" You will see a few settings which are typically driver specific. The important value to change for the Access driver, for example, is the DBQ value. That's actually the file name of the Access database.

Random Links

These are in need of sorting and annotating. Some are relevant only to ODBC developers (but I don't want to loose them).

        http://www.ids.net/~bjepson/freeODBC/index.html

        http://dataramp.com/

        http://www.openlink.co.uk

        http://www.syware.com

        http://www.microsoft.com/odbc
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