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I am receiving a "Couldn't fetch mysqli" error on the following function when trying to import data from a text file. However the insert function is working just fine in other places. The data from the file is being parsed correctly, and the query works fine when I copy and past it into PHPMyAdmin.


1. $conn = mysqli_connect("localhost","xxxxx","xxxxx","xxxx") OR die("Error!!");
2. function insert ($query){
3.  global $conn;
4.  if (!$conn) {
5.          die("Connection failed: " . mysqli_connect_error());
6.  }
7.  if (mysqli_query($conn, $query)){
8.      $result = "<b>Inserted $query</b>n<br />";
9.      return $result;
10. } else {
11.     echo "Error: ". $query . "<br />" . mysqli_error($conn);
12. }
14. mysqli_close($conn);
15. }

The query I am trying to insert is:

INSERT INTO movies VALUES( '2603', 'Miracle Season, The', 'The Miracle Season', '2019-04-01',
'2D', '9', '101', '10', 'PG', 'for some thematic elements.', '', 'Scope', '01:30:55' )

I am calling the function by $result = insert($query);

The "couldn't fetch mysqli" error is on line 7. I'm also getting the error on line 11 and line 14.

As I said above, the function is working fine with other scripts and the query works fine when I try to run it manually.

One additional note is the inserted items do not contain an auto increment id because the first value of the query is already a unique id from another database. My import function checks the id to see if it already exists and runs an update or insert query depending on whether the row exists.



I suspect you're calling the function multiple times. But it calls mysqli_close($conn) at the end, so when you try to use it the next time you get an error, because $conn can't be used any more.

Get rid of that line, and close the connection when the script is all done using MySQL (or don't bother, it will be closed automatically when the script ends).

Thursday, October 13, 2022

Probably somewhere you have DBconnection->close(); and then some queries try to execute .

Hint: It's sometimes mistake to insert ...->close(); in __destruct() (because __destruct is event, after which there will be a need for execution of queries)

Wednesday, August 24, 2022

I went ahead and ran a test where one query uses a prepared statement, and the other builds the entire query then executes that. I'm probably not making what I'm wanting to know easy to understand.

Here's my test code. I was thinking prepared statements sort of held back execution until a $stmt->close() was called to optimize it or something. That doesn't appear to be the case though as the test that builds the query using real_escape_string is at least 10 times faster.


$db = new mysqli('localhost', 'user', 'pass', 'test');

$start = microtime(true);
$a = 'a';
$b = 'b';

$sql = $db->prepare('INSERT INTO multi (a,b) VALUES(?, ?)');
$sql->bind_param('ss', $a, $b);
for($i = 0; $i < 10000; $i++)
    $a = chr($i % 1);
    $b = chr($i % 2);

echo microtime(true) - $start;


Sunday, November 6, 2022

This actually depends on the Mysql server. The default max size for all data combined in the entire query is 1mb. See:

If your data combined is under that "max_allowed_packet" threshold, just use "s" for the binding type for any text field. Infact, you can usually get away with using "s" for any field type at all (date, float, etc).

If your entire entry combined that you want to insert is over 1mb (or whatever you reset it to) in length, you'll want to use mysqli_stmt::send_long_data method and the "b" binding type to send this particular field in chunks.

Wednesday, August 24, 2022

Your connection has been closed, after execution of first SELECT Statement, it means connection closed to early:


You need to use close() after your all queries or re build connection. ist one is the better option.

You are getting user input $_REQUEST['key'], it means your query is open for SQL injection, this will help you to understand how can you prevent your code with SQL injection: How can I prevent SQL injection in PHP?

Wednesday, August 3, 2022
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