PDO bindParam 参数length没看懂

Question

来自https://www.php.net/manual/zh...
$sth->bindParam(':colour', $colour, PDO::PARAM_STR, 12);
12是啥意思？没看懂

<?php
$calories = 150;
$colour = 'red';
$sth = $dbh->prepare('SELECT name, colour, calories

FROM fruit
WHERE calories < :calories AND colour = :colour');

$sth->bindParam(':calories', $calories, PDO::PARAM_INT);
$sth->bindParam(':colour', $colour, PDO::PARAM_STR, 12);
$sth->execute();

Answer 1

一样的问题。

• php - PDO PARAM_STR and length - Stack Overflow

还有一个类似的问题

• php - PDOStatement::bindParam, using PDO::PARAM_STR what does the length specify? - Stack Overflow