MySQLI 命令后发生的 PHP Echo 语句

Question

我有一个 php，用于清理一些 MySQL 数据表（truncate 命令），并输出到屏幕上一些指示该任务已完成的消息（ECHO 语句）。

然后 PHP 通过 LOAD DATA INFILE 命令将几个 CSV 文件加载到最近清理的数据库表中。这后面是几个 echo 语句，表示任务已完成。

我遇到的问题是所有输出到屏幕都是在 MYSQL 工作完成之后。我希望在 MYSQL 进程之前使用 echo 语句，这可能需要一分钟或更长时间，以便用户知道该进程正在进行中并且可能需要一些时间。

echo "<center><strong>Cleaning up tables in preparation of importing data files...<strong></center><br>";

//select the database we are going to be using
mysqli_select_db($conn, "database");

//truncate (empty) the three tables
mysqli_query($conn, 'TRUNCATE TABLE firsttable;');
mysqli_query($conn, 'TRUNCATE TABLE secondtable;');
mysqli_query($conn, 'TRUNCATE TABLE thirdtable;');

//provide feedback on process
echo "<center><strong>Tables cleaned!</strong></center><br>";

//queries which will load datafiles into the tables
$query = "LOAD DATA INFILE \"D:/wamp64/www/folder/firsttable.csv\" INTO TABLE altoccurrences COLUMNS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '\"' ESCAPED BY '\"' LINES TERMINATED BY '\n' IGNORE 1 LINES";
$query2 = "LOAD DATA INFILE \"D:/wamp64/www/folder/secondtable.csv\" INTO TABLE altimages COLUMNS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '\"' ESCAPED BY '\"' LINES TERMINATED BY '\n' IGNORE 1 LINES";
$query3 = "LOAD DATA INFILE \"D:/wamp64/www/folder/thirdtable.csv\" INTO TABLE altidentifications COLUMNS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '\"' ESCAPED BY '\"' LINES TERMINATED BY '\n' IGNORE 1 LINES";

//send queries to MySQL and check for potential errors.
$result = mysqli_query($conn, $query) or die ('Could not connect to mysqli: ' . mysqli_error($conn));
$result2 = mysqli_query($conn, $query2)  or die ('Could not connect to mysqli: ' . mysqli_error($conn));
$result3 = mysqli_query($conn, $query3)  or die ('Could not connect to mysqli: ' . mysqli_error($conn));

//provide feedback on process
echo "<center><h2><strong>Your Files Have Been Inserted into Database!</strong></h2></center><br>";

Answer 1

PHP 通常会在发送内容之前对其进行缓冲。在每次回显后尝试以下代码，尝试强制 PHP 立即发送数据。

@flush();