MySQLI命令后发生的PHP Echo语句

Question

I have a php which is meant to clean up a few MySQL data tables (truncate command), and output to screen a few messages indicating that task was completed (ECHO statements).

The PHP then loads several CSV files into the recently cleaned database tables via LOAD DATA INFILE command. This is Followed by few echo statements to indicate the task completed.

The problem I am having is that all output to screen is only after the MYSQL work is completed. I would like to have the echo statements precede a MYSQL process which may take a minute or more so that the user knows that the process is ongoing and may take some time.

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 '
' 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 '
' 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 '
' 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 usually buffers content before sending it out. Try the following code after each echo to try and force PHP to send the data out immediately.

@flush();