This code is supposed to do a SQL insert using the contents of the hash %$c.

In the values section of the SQL statement, I need a string of the form "?,?,?" where there is a ? for each field, and all the ?s are delimited by commas. However, there can not be a trailing comma at the end or syntax errors in the database (PostgreSQL) result.

I tried

my $sth = $dbh->prepare(
  'INSERT INTO table('
  . join(',', keys %$c)
  . ") VALUES ("
  . chop(join('', map {'?,'} keys %$c))
  . ")"
);

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I managed to make the code work by taking it out and explicitly assigning the value of the expression to a scalar, $placeholderstr. I would like to inline the rvalue of the first line of this code in the $dbh->prepare() statement. Any ideas?

code:

my $placeholderstr = join('', map {'?,'} keys %$c);
chop $placeholderstr;

my $sth = $dbh->prepare(
  'INSERT INTO table('
  . join(',', keys %$c)
  . ") VALUES ($placeholderstr)"
);

$sth->execute(values %$c) or die $dbh->errstr;

[download]

In reply to Can't I chop the lvalue of join? by DapperDan

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