从MYSQL选择Blob,获取空值 [英] Selecting Blob from MYSQL, getting null
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问题描述
从MySQL中选择Blob时,我需要做些特别的事情吗?对于以下内容,我得到一个NULL(数据是一个中等级别的文件,file_extension是varchar):
Is there anything special I need to do when selecting a blob from MySQL? I get a NULL for the following (data is a mediumblob, file_extension is varchar):
$sql = "SELECT data, file_extension FROM table1 WHERE table1.id = ?";
$q = $con->prepare($sql);
$q->execute(array(1));
if ($q->rowCount() == 0)
{
disconnectSqlConnection($con);
$arr = array('success' => 'false',
'error' => -2);
return json_encode($arr);
}
else
{
$row = $q->fetch();
$arr = array('success' => 'true',
'data' => $row[0],
'extension' => $row[1]);
disconnectSqlConnection($con);
return json_encode($arr);
}
$ row [1]具有"pdf",这是正确的. $ row [0]为NULL,但在数据库中,我看到大小为244.8KB的blob
$row[1] has 'pdf', which is correct. $row[0] is NULL, but in the database, I see a blob of size 244.8KB
有什么想法吗?
推荐答案
使用CAST
将其转换为文本
$sql = "SELECT CAST(data AS CHAR(10000) CHARACTER SET utf8) as data, file_extension FROM table1 WHERE table1.id = ?";
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