PDO准备好的语句fetch()返回双精度结果

问题描述

我有一个输出到CSV文件的脚本.但是，即使数据库中当前只有一行，但我得到的输出却在表的每一行中回显了每一列两次.

I have a script that is outputting to a CSV file. However, even though there is currently one row in the database, the output I'm getting is echoing out each column from each row in the table twice.

例如:1,1，约翰，约翰，史密斯，史密斯，2014年，2014年应该1，约翰，史密斯，2014

For example:1,1,John,John,Smith,Smith,2014,2014Should be1,John,Smith,2014

在我使用PDO和准备语句之前，这很好用，所以我想也许我不了解fetch()如何正确工作.下面是我的代码.知道我做错了什么吗?

This worked fine before I went with PDO and prepared statements, so I'm thinking maybe I'm not understanding how fetch() works correctly.Below is my code. Any idea what I could be doing wrong?

// get rows
$query_get_rows = "SELECT * FROM Contacts ORDER BY date_added DESC";
$result_get_rows = $conn->prepare($query_get_rows);
$result_get_rows->execute();
$num_get_rows = $result_get_rows->rowCount();

while ($rows_get_rows = $result_get_rows->fetch())
{
  $csv .= '"'.join('","', str_replace('"', '""', $rows_get_rows))."\"\n";
}
echo $csv;
exit;

推荐答案

您应该对PDO说，您只需要一个关联数组或带编号的数组:

You should say to PDO, that you want only an associative array or a numbered array:

while ($rows_get_rows = $result_get_rows->fetch(PDO::FETCH_ASSOC))

获取关联数组或

while ($rows_get_rows = $result_get_rows->fetch(PDO::FETCH_NUM))

获取由列号索引的数组

来自 PDOStatement :: fetch

控制如何将下一行返回给调用方. 该值必须是PDO :: FETCH_ *常量之一，默认为 PDO :: ATTR_DEFAULT_FETCH_MODE的值(默认为 PDO :: FETCH_BOTH).

Controls how the next row will be returned to the caller. This value must be one of the PDO::FETCH_* constants, defaulting to value of PDO::ATTR_DEFAULT_FETCH_MODE (which defaults to PDO::FETCH_BOTH).

PDO :: FETCH_ASSOC:返回按列名索引的数组 在您的结果集中

PDO::FETCH_ASSOC: returns an array indexed by column name as returned in your result set

PDO :: FETCH_BOTH(默认):返回由两列索引的数组 名称和结果索引中返回的0索引列号

PDO::FETCH_BOTH (default): returns an array indexed by both column name and 0-indexed column number as returned in your result set

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