Chapter Objectives

• Build simple DBI programs
• Follow the prepare/execute/finish model
• Display the contents of a database table

Lab: A CGI script that:

• connects to a database and dumps one of its tables

• uses SQL:   SELECT * FROM title

• uses these DBI routines:
  • connect -- establish connection to remote database -- example:

    $dbh = DBI->connect("DBI:$DB_type:test_nile", $DB_login, $DB_password);

  • optional: prevent data truncation -- tell ODBC not to truncate the stream of data it returns (by default, it returns only the first 256 bytes) -- example:

    $dbh->{'LongReadLen'} = 20000;

  • prepare -- send SQL statement to remote database -- example:

    $sth = $dbh->prepare(q{SELECT * from title});

  • execute -- tell remote database to do the SQL statement -- example:

    $sth->execute;

  • dump_results -- get the result (zero or more rows) as an unformatted stream of text

  • finish -- tell remote database to free the resources used by the previous SQL statement -- example:

    $sth->finish;

  • disconnect -- terminate connection to remote database -- example:

    $dbh->disconnect;

Summary