更優雅的方式來構建SQL添加WHERE並使用佔位符

Question

構建具有各種WHERE條件的sql的最佳方式是什麼？ 我的解決方案看起來醜陋：

my ($where, @values); 
if ($phone_number) 
{ 
    $where = 'AND pnone_number=?'; 
    @values = ($from, $till, $phone_number); 
} 
else 
{ 
    $where = ''; 
    @values = ($from, $till); 
} 
my $sql = 'SELECT * FROM calls WHERE time between ? AND ? '.$where.' ORDER BY time'; 
my $res = $dbh->selectall_arrayref($sql, undef, @values) or warn 'error'; 

Answer 1

如何：

my $where = ''; 
my @values = ($from, $till); 

if ($phone_number) { 
    $where = 'AND phone_number=?'; 
    push @values, $phone_number; 
} 

，消除了您的else條款的必要性。

你也可以使用類似SQL::Abstract的東西。

use SQL::Abstract; 

... 

my ($sql, @values) = SQL::Abstract->new->select(
    'calls',             # table 
    '*',              # columns 
    { time => { '<=' => $till, '>' => $from },     # where clause 
     $phone_number ? (phone_number => $phone_number) : (), 
    }, 
    'time'              # order clause 
); 

Answer 2

1=1的案件時加入$where將epmty。

my $where = "AND time between ? AND ? "; 
my @values = ($from, $till); 

if ($phone_number) { 
    $where .= 'AND pnone_number=? '; 
    push @values, $phone_number; 
} 

my $sql = 'SELECT * FROM calls WHERE 1=1 $where ORDER BY time'; 
my $res = $dbh->selectall_arrayref($sql, undef, @values) or warn 'error'; 

Answer 3

條件列表包括（又名"enterprise"）：

my @values = ($from, 
       $till, 
       ($phone_number) x !! $phone_number, 
      ); 

my $sql = 'SELECT * FROM calls WHERE time between ? AND ? ' 
     . 'AND phone_number=?' x !! $phone_number 
     . ' ORDER BY time';