Re(2): (Ovid): uninitialized value in concatenation

When calling $sth->fetchrow_array in a scalar context, you're going to get back an array ref, possibly containing some other array refs (your result rows). So your test, if ($name eq "") {, should probably look more like, if ($name->[0][0] eq "") {, except that this completely disregards the case where no rows are returned.

You might also factor out all of the common code and elminate unnecessary complexity:

my $name = undef;

# store subparent for each parent
my %parent_hash = ( 'Father' => 'Mother',
                    'Mother' => 'Father' );

if (exists $parent_hash{$parent}) {
  my $sub_parent = $parent_hash{$parent};

  for my $col ( $parent, $sub_parent ) {
    my $sql = "select $col from Roster where User=?";

    my $rv = $dbh->selectcol_arrayref( $sql, undef, $user );
    if ( @$rv ) {  # any rows returned?
      $name = $rv->[0];  # take first one
      last;
    }
  }
}
# here, $name will be defined if one of above succeeded

# etc. ...
[download]

Also, why are you using prepared statements (e.g., prepare() and execute()) without placeholders ('?'). You can just call selectrow_arrayref($sql) (or in your case, selectcol_arrayref($sql) since the results will be a single column) to the same effect.

Update: added placeholders, as per cfreak. What was I thinking?

dmm

If you GIVE a man a fish you feed him for a day
But, TEACH him to fish and you feed him for a lifetime

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Re: Re(2): (Ovid): uninitialized value in concatenation by mnlight (Scribe) on Jan 15, 2002 at 10:35 UTC
This code is not working because the sql is returning a '' value and the if statement is seeing it as being true. what can I change so it evaluates the '' as no value returned. `# store subparent for each parent my %parent_hash = ( 'Father' => 'Mother', 'Mother' => 'Father' ); if (exists $parent_hash{$parent}) { my $sub_parent = $parent_hash{$parent}; for my $col ( $parent, $sub_parent ) { my $sql = "select $col from Roster where User=?"; my $rv = $dbh->selectcol_arrayref( $sql, undef, $user); if ( @$rv) { # any rows returned? $name = $rv->[0]; # take first one last; } } }` [download]	[reply] [d/l]
Re: (4): (Ovid): uninitialized value in concatenation by dmmiller2k (Chaplain) on Jan 15, 2002 at 20:17 UTC
"... the sql is returning a '' value and the if statement is seeing it as being true." This is not correct. As written, the `if` statement is not testing for truth or falseness, but whether or not any rows were returned. To accomplish what you seek, change the `if` statement to read: `if ( @$rv && $rv->[0] ) { # any NON-BLANK rows returned?` [download] dmm	[reply] [d/l] [select]
Re: Re(2): (Ovid): uninitialized value in concatenation by IlyaM (Parson) on Jan 15, 2002 at 00:31 UTC
When calling $sth->fetchrow_array in a scalar context, you're going to get back an array ref, possibly containing some other array refs (your result rows). It is not correct. $sth->fetchrow_array in a scalar context returns the value of the first field. -- Ilya Martynov (http://martynov.org/)	[reply]
Re: Re(2): (Ovid): uninitialized value in concatenation by mnlight (Scribe) on Jan 15, 2002 at 02:29 UTC
In this `my $name = undef; # store subparent for each parent my %parent_hash = ( 'Father' => 'Mother', 'Mother' => 'Father' ); if (exists $parent_hash{$parent}) { my $sub_parent = $parent_hash{$parent}; for my $col ( $parent, $sub_parent ) { my $sql = "select $col from Roster where User=?"; my $rv = $dbh->selectcol_arrayref( $sql, undef, $user ); if ( @$rv ) { # any rows returned? $name = $rv->[0]; # take first one last; } } } # here, $name will be defined if one of above succeeded` [download] what is the undef do inside the `my $rv = $dbh->selectcol_arrayref( $sql, undef, $user );` [download]	[reply] [d/l] [select]
Re(4): (Ovid): uninitialized value in concatenation by dmmiller2k (Chaplain) on Jan 15, 2002 at 20:00 UTC
From the `DBI` docs: `selectrow_array @row_ary = $dbh->selectrow_array($statement); @row_ary = $dbh->selectrow_array($statement, \%attr); @row_ary = $dbh->selectrow_array($statement, \%attr, @bind_values);` [download] where the third form is the one I was using, without specifying any attributes (i.e., `undef`). dmm If you GIVE a man a fish you feed him for a day But, TEACH him to fish and you feed him for a lifetime	[reply] [d/l] [select]
Re(4): (Ovid): uninitialized value in concatenation by dmmiller2k (Chaplain) on Jan 15, 2002 at 20:01 UTC
From the `DBI` docs: `selectrow_array @row_ary = $dbh->selectrow_array($statement); @row_ary = $dbh->selectrow_array($statement, \%attr); @row_ary = $dbh->selectrow_array($statement, \%attr, @bind_values);` [download] where the third form is the one I was using, without specifying any attributes (i.e., `undef`). dmm	[reply] [d/l] [select]
Re: Re(2): (Ovid): uninitialized value in concatenation by mnlight (Scribe) on Jan 14, 2002 at 23:33 UTC
Please explain how I can eliminate some of the complexity.	[reply]
Re: (4): uninitialized value in concatenation by dmmiller2k (Chaplain) on Jan 14, 2002 at 23:43 UTC
To start with, you could eliminate redundancies (as I've tried to demonstrate by refactoring your code), and encapsulate data dependencies in a data structure, to the degree possible (see `my %parent_hash` in my snippet), rather than `if` statements.	[reply] [d/l] [select]
Re: Re: (4): uninitialized value in concatenation by mnlight (Scribe) on Jan 15, 2002 at 00:33 UTC
I have taken your code and put in my script it works the problem I am having is somehow it does not recognize who the parent is and give send it to $name. # store subparent for each parent my %parent_hash = ( 'Father' => 'Mother', 'Mother' => 'Father' ); if (exists $parent_hash{$parent}) { my $sub_parent = $parent_hash{$parent}; for my $col ( $parent, $sub_parent ) { my $sql = "select $col from Roster where User=?"; my $rv = $dbh->selectcol_arrayref( $sql, undef, $user ); if ( @$rv ) { # any rows returned? $name = $rv->[0]; # take first one last; } } } foreach $date ( @volunteer_date ) { $sth = $dbh->prepare ("select distinct Volunteer from Voluntee +r where Volunteer = \'$name\' and Date = \'$date\'"); $sth->execute (); my $chk = $sth->fetchrow_array; #Verify the parent is not signed up. if ($chk eq $name){ print $query->h1({-align=>'center'}, "You are already signed u +p for this date: $date"); } #end if statement #process the information and update the schedule. else{ $sth = $dbh->prepare ("select max(Number) from Volunteer where Date = '$date' and Volunteer = 'TBD'"); $sth->execute (); my $number = $sth->fetchrow_array; $sth = $dbh->prepare ("update Volunteer set Volunteer = '$name' where Date = '$date' and Volunteer = 'TBD' and Number = $number "); $sth->execute (); print $query->h1({-align=>'center'}, "You signed up for this d +ate $date") [download]	[reply] [d/l]