PostgreSQL, Second Edition

Client 3—Processing Queries

Now, let's turn our attention to query processing. DBI treats SELECT commands and non-SELECT commands differently. Commands other than SELECT require less-complex processing, so let's look at those first. Listing 14.6 shows the source code for client3a:

Listing 14.6. client3a.pl

1 #!/usr/bin/perl -W 2 # 3 # Filename: client3a.pl 4 # 5 6 use strict; 7 use DBI; 8 9 my $dbh = DBI->connect( "dbi:Pg:", undef, undef, {PrintError => 0} ) 10 or die "Can't connect to PostgreSQL: $DBI::errstr ($DBI::err)\n"; 11 12 my $rows = $dbh->do( $ARGV[0] ); 13 14 if( !defined( $rows )) { 15 print( $dbh->errstr."(".$dbh->err().")\n" ); 16 } 17 else { 18 print( "Ok: $rows rows affected\n" ); 19 } 20 21 $dbh->disconnect();

After successfully ...