PHP MySQLi: errno() function

mysqli_errno() function / mysqli::$errno

The mysqli_errno() function / mysqli::$errno return the last error code for the most recent function call, if any.


Object oriented style

int $mysqli->errno;

Procedural style

int mysqli_errno ( mysqli $link )

Usage: Procedural style



Name Description Required/Optional
connection Specifies the MySQL connection to use Required

Return value:

An error code value for the last call, if it failed. zero means no error occurred.

Version: PHP 5, PHP 7

Example of object oriented style:

$mysqli = new mysqli("localhost", "user1", "datasoft123", "hr");

/* check connection */
if ($mysqli->connect_errno) {
    printf("Connect failed: %s\n", $mysqli->connect_error);

if (!$mysqli->query("SET a=1")) {
    printf("Errorcode: %d\n", $mysqli->errno);

/* close connection */


Errorcode: 1193

Example of procedural style:


$link = mysqli_connect("localhost", "user1", "datasoft123", "hr");

/* check connection */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s\n", mysqli_connect_error());

if (!mysqli_query($link, "SET a=1")) {
    printf("Errorcode: %d\n", mysqli_errno($link));

/* close connection */


Errorcode: 0


// Check connection
if (mysqli_connect_errno())
  echo "Failed to connect to MySQL: " . mysqli_connect_error();

// Perform a query, check for error
if (!mysqli_query($con,"INSERT INTO employees (First_Name) VALUES ('David')"))
  echo("Errorcode: " . mysqli_errno($con));


Sample Output:


See also

PHP Function Reference

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Next: error_list

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PHP: Tips of the Day

PHP: Correct file permissions for WordPress

When you setup WP you (the webserver) may need write access to the files. So the access rights may need to be loose.

chown www-data:www-data  -R * # Let Apache be owner
find . -type d -exec chmod 755 {} \;  # Change directory permissions rwxr-xr-x
find . -type f -exec chmod 644 {} \;  # Change file permissions rw-r--r-

After the setup you should tighten the access rights, according to Hardening WordPress all files except for wp-content should be writable by your user account only. wp-content must be writable by www-data too.

chown <username>:<username>  -R * # Let your useraccount be owner
chown www-data:www-data wp-content # Let apache be owner of wp-content

Maybe you want to change the contents in wp-content later on. In this case you could

  • temporarily change to the user to www-data with su,
  • give wp-content group write access 775 and join the group www-data or
  • give your user the access rights to the folder using ACLs.

Whatever you do, make sure the files have rw permissions for www-data.

Ref : https://bit.ly/3hcrTkL


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