OLE and ODBC: Taming the Technologies The Third Annual Perl Conference, 1999 Sunday, August 22, 1999Roth Consulting ODBC

OLE and ODBC: Taming the Technologies (ODBC) 2 Uses SQL Requires ODBC to be installed Win32::ODBC supports access into the ODBC API ODBC: Open DataBase Connectivity

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 3 ODBC Options Perl can access ODBC –Win32::OLE ( OLEDB, ADO ) Memory & processor overhead Not guaranteed to be ODBC or SQL Some bugs yet to be ironed out (eg. SQL Server and multiple text columns) –ODBCTie Is this still maintained? –DBI General DBI rules apply Cross platform –Win32::ODBC Requires Win32 machine

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 4 Who uses Perl and ODBC? Unbelievable amount of Perl and ODBC use –Database maintenance –Administration –Web commerce –Inter/intranet data access Professional Applications –Digital Paper’s Intranet Docs (IDOC) product Partner with Xerox 99% Perl based Can serve up to 2 million documents

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 5 What drivers are installed? Enumerate installed ODBC drivers with: %Drivers = Win32::ODBC::Drivers() –Returns a hash –Hash keys are driver names –Hash value is string with driver specific attributes delimited by semicolons: “ Attrib1=Value1;Attrib2=Value2;Attribn=Valuen ”

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 6 DSN: Data Source Name All database connections begin with a DSN Named database configuration Three types: –User DSN –System DSN –File DSN Win 95/98 only understand User and File When used as a CGI/ASP script with a web server always use System DSN!

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 7 DSN: Data Source Name Create manually using the ODBC control panel applet Create using Win32::ODBC::ConfigDSN() ConfigDSN( $Action, $Driver, $Attrib1, $Attribn ) –Actions ODBC_ADD_DSNAdd new DSN ODBC_MODIFY_DSNModify existing DSN ODBC_REMOVE_DSNRemove existing DSN ODBC_ADD_SYS_DSNAdd new system DSN ODBC_MODIFY_SYS_DSNModify existing system DSN ODBC_REMOVE_SYS_DSNRemove existing system DSN –Driver depends upon installed drivers (keys from Win32::ODBC::Drivers() ): Microsoft Access Driver (*.mdb) II

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 8 DSN: Data Source Name –Attributes are any valid ODBC driver keywords One required keyword: –DSN=Foo Other keywords differ based on ODBC driver Best way to discover keywords is by reading docs or manually creating a DSN then examining the Registry Do not include a “ Driver ” keyword III

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 9 DSN: Data Source Name use Win32::ODBC; # Create a DSN... Win32::ODBC::ConfigDSN( ODBC_ADD_DSN, $Driver, "DSN=My DSN Name", "Description=A Test DSN", "DBQ=c:\\temp\\$MyData.mdb", "DEFAULTDIR= C:\\Database", "UID=Admin", "PWD=Adminpassword" ); IV

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 10 Connecting Create a new Win32::ODBC object: $db = new Win32::ODBC( "My DSN" ); The DSN can either be the name of a DSN or it can be a full connect string: –“ My DSN ” –“ DSN=My DSN;UID=Foo;PWD=Bar ” If the DSN passed in is really a Win32::ODBC object then that object is “cloned” $db2 = new Win32::ODBC( $db ); –$db2 is identical to $db but with different STMT’s –Some database systems do not like such clones

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 11 Executing SQL Statement Submit a text based SQL query $Result = $db->Sql( “SELECT * FROM Foo” ); This is the only method call which returns a non- false value upon failure –Returns error number (ODBC driver specific; not really valuable) –Call $db->Error() for more error details

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 12 Call FetchRow() until it returns false Collect the data with Data() or DataHash() while( $db->FetchRow() ) { my( %Data ) = $db->DataHash(); …process data… } Fetching Results

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 13 Batch Queries If you submitted a batch query or a stored procedure returns multiple result sets repeat the FetchRow() process until MoreResults() returns FALSE. do { while( $db->FetchRow() ) { my( %Data ) = $db->DataHash(); …process data… } } while( $db->MoreResults() );

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 14 Closing The Connection To close the database connection call Close() $db->Close();

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 15 Transactions By default an ODBC connection is in AutoCommit mode –All transactions are committed to the database immediately Turn off AutoCommit mode with: $db->SetConnectOption($db->SQL_AUTOCOMMIT, $db->SQL_AUTOCOMMIT_OFF ); Perform queries (select, insert, delete, update, etc) To commit or rollback call Transact(): $db->Transact( $db->SQL_COMMIT ); $db->Transact( $db->SQL_ROLLBACK );

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 16 Row Counts Report number of rows in the result set with: $db->RowCount(); Not all ODBC drivers support it Some ODBC drivers only support it for insert and delete Alternative is to issue a SQL count query: SELECT Count(*) FROM Foo –The result set is one row and one column containing a value which is the number of rows

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 17 Connection Options You can set and query connection options with: $db->GetConnectOption( $Option ); $db->SetConnectOption( $Option, $Value ); SetConnectOption() returns TRUE if successfully set and FALSE if it failed to set the option GetConnectOption() returns the current value of the specified option. It does not return any errors!

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 18 Connection Option Examples To discover the current qualifier (SQL Server this is the database, in Access it is the.mdb file): $Row = $db->GetConnectOption( $db-> SQL_CURRENT_QUALIFIER ); To change the login timeout value (in seconds): $db->SetConnectOption( $db->SQL_LOGIN_TIMEOUT, 10 ); Query the ODBC trace log file: $db->GetConnectOption($db->SQL_OPT_TRACEFILE ); Set ODBC trace logging to on: $db->SetConnectOption($db->SQL_OPT_TRACE, $db->SQL_OPT_TRACE_ON );

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 19 Special Connect Options Some connection options must be set before the connection to the database is performed Pass these into the new() function: $db = new Win32::ODBC( $Dsn, ODBC::SQL_LOGIN_TIMEOUT => 10, ODBC::SQL_OPT_TRACEFILE => ‘c:\trace.log’, ODBC::SQL_OPT_TRACE => ODBC::SQL_OPT_TRACE_ON );

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 20 Stmt Options Every time you submit a command to the database (such as a query) call it a statement or a stmt (for short) You can set and query options for stmt’s with: $db->GetStmtOption( $Option ); $db->SetStmtOption( $Option, $Value ); SetStmtOption() returns TRUE if successfully set and FALSE if it failed to set the option GetStmtOption() returns the current value of the specified option. It does not return any errors!

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 21 Stmt Option Examples To discover the current row: $Row = $db->GetStmtOption( $db->SQL_ROW_NUMBER ); To change the query timeout value (in seconds): $db->SetStmtOption( $db->SQL_QUERY_TIMEOUT, 10 ); Set the driver to not scan the query for escape clauses: $db->SetStmtOption($db->SQL_NOSCAN, $db->SQL_NOSCAN_ON );

Roth ConsultingOLE and ODBC: Taming the Technologies (ODBC) 22 Programming DBI, by Tim Bunce and Alligator Descartes, O’Reilly & Associates. Win32 Perl Programming: The Standard Extensions, Dave Roth, MacMillan Publishing. Win32 Scripting Journal, The Perl Journal, Other Sources Of Information Programming DBI, by Tim Bunce and Alligator Descartes, O’Reilly & Associates. Win32 Perl Programming: The Standard Extensions, Dave Roth, MacMillan Publishing. Win32 Scripting Journal, The Perl Journal,

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