$image = file_get_contents($_FILES['image_field_name']['tmp_name']);

然后在数据库中插入图像试试这个：

$sql = "INSERT INTO table (id,image) VALUES(1,empty_blob()) RETURNING image INTO :image";

$result = oci_parse($connection,$sql);
$blob = oci_new_descriptor($connection,OCI_D_LOB);
oci_bind_by_name($result,":image",$blob,-1,OCI_B_BLOB);
oci_execute($result,OCI_DEFAULT) or die ("Unable to execute query");

if(!$blob->save($image)) {
    oci_rollback($connection);
}
else {
    oci_commit($connection);
}

oci_free_statement($result);
$blob->free();