perl DBI执行不识别'？'

Question

我有这样的代码：

if($update[$entity_id]) 
{ 
    my $sql = "UPDATE cache SET date = '?', value = '?' WHERE item_id = ? AND level = ? AND type = ?;"; 
} 
else 
{ 
    my $sql = "INSERT INTO cache (date, value, item_id, level, type) VALUES ('?','?',?,?,?);"; 
} 
my $db = $self->{dbh}->prepare(q{$sql}) or die ("unable to prepare"); 
$db->execute(time2str("%Y-%m-%d %X", time), $stored, $entity_id, 'entity', 'variance'); 

但是，当它要运行的更新我得到这个错误：

DBD::Pg::st execute failed : called with 5 bind variables when 0 are needed.

为什么？

Answer 1

如果你已经转向了严格的和/或警告，你会看到你的问题是什么。

你写了

if (...) { 
    my $sql = ...; 
} else { 
    my $sql = ...; 
} 
execute($sql); 

这意味着您在if分支声明$sql变量不在范围和你要执行完全是空的SQL。

Answer 2

你正在准备字面'$sql'，但那不是你唯一的问题，词汇$sql变量超出{}以外的范围。

尝试，

use strict; 
use warnings; 
#... 

my $sql; 
if($update[$entity_id]) 
{ 
    $sql = "UPDATE cache SET date = ?, value = ? WHERE item_id = ? AND level = ? AND type = ?"; 
} 
else 
{ 
    $sql = "INSERT INTO cache (date, value, item_id, level, type) VALUES (?,?,?,?,?)"; 
} 
my $st = $self->{dbh}->prepare($sql) or die ("unable to prepare"); 
$st->execute(time2str("%Y-%m-%d %X", time), $stored, $entity_id, 'entity', 'variance');