{"id":309,"date":"2016-08-07T03:53:58","date_gmt":"2016-08-07T00:53:58","guid":{"rendered":"https:\/\/community.virtono.com\/?p=309"},"modified":"2023-06-21T09:12:11","modified_gmt":"2023-06-21T06:12:11","slug":"how-to-handle-mysql-errors","status":"publish","type":"post","link":"https:\/\/www.virtono.com\/community\/tutorial-how-to\/how-to-handle-mysql-errors\/","title":{"rendered":"How to Handle MySQL Errors"},"content":{"rendered":"

This article is a fraction of a Number of Articles on MySQL, to access them click here<\/a>.<\/p>\n

\"62925050\"<\/p>\n

Handling MySQL Errors<\/strong><\/p>\n

You use the mysqli functions of the PHP language, such as mysqli_connect and mysqli_query, to interact with the MySQL database. Things will sometimes go wrong when you use the statements. You may make an error in your typing, such as mistyping a database name. Sometimes, problems arise that you can\u2019t avoid, such as the database or the network being down. You need to include code in your script that handles error situations.<\/p>\n

For instance, suppose that you\u2019re using an account called root to access your database and you make a typo, as in the following statements:<\/p>\n

$host = \u201clocalhost\u201d;<\/p>\n

$user = \u201crot\u201d;<\/p>\n

$password = \u201c\u201d;<\/p>\n

$cxn = mysqli_connect($host,$<\/em>user,$<\/em>password)<\/p>\n

Because you type \u201crot\u201d rather than \u201croot\u201d, you see a warning message similar to this one:<\/p>\n

Warning: <\/strong>Access denied for user: \u2018rot@localhost\u2019 (Using password: NO) …<\/p>\n

The preceding error message contains the information that you need to figure out the problem \u2014 it shows your account name that includes the typo. However, after your script is running and customers are using it, you don\u2019t want your users to see a technical error message that shows your user ID. You want to turn the PHP errors off or send them to an error log file. You could then use a die statement to stop the script and display a polite message to the user, as follows:<\/p>\n

$cxn = mysqli_connect($host,$<\/em>user,$<\/em>password) or die(\u201cThe Catalog is not available at the moment. Please try again later.\u201d);<\/p>\n

When a mysqli_query() function fails, MySQL returns an error message that contains information about the cause of the failure. However, this message isn\u2019t displayed unless you specifically display it. Again, you may want to see these messages when you\u2019re developing the script, but you may not want to display them to the public. You can display the MySQL error that\u2019s returned by using the following function:<\/p>\n

mysqli_error($cxn)<\/p>\n

AUDIA4<\/p>\n

For example<\/strong>, you might include the function in your code, as follows:<\/p>\n

$query = \u201cSELECT * FROM Cust\u201d;<\/p>\n

$result = mysqli_query($cxn,$query)<\/p>\n

or die (\u201cError: \u201c.mysqli_error($cxn));<\/p>\n

In this example, if the function call fails, the die statement displays the<\/p>\n

MySQL error, which might be something like this:<\/p>\n

Error: Table \u2018catalog.cust\u2019 doesn\u2019t exist<\/p>\n

Occasionally, you may want to perform additional actions if the function fails, such as delete variables or close the database connection. You can perform such actions by using a conditional statement:<\/p>\n

if(!$result = mysqli_query($cxn,$query))<\/p>\n

{<\/p>\n

echo mysqli_error($cxn);<\/p>\n

unset($auth);<\/p>\n

exit();<\/p>\n

}<\/p>\n

If the function call fails, the statements in the if block are executed. The echo statement displays the MySQL error returned by the function. A variable is removed, and the script exits.<\/p>\n

Notice the ! (exclamation point) in the if statement. ! means \u201cnot\u201d. In other words, the if statement is true if the assignment statement is not true.<\/p>\n","protected":false},"excerpt":{"rendered":"

This article is a fraction of a Number of Articles on MySQL, to access them click here. Handling MySQL Errors You use the mysqli functions of the PHP language, such as mysqli_connect and mysqli_query, to interact with the MySQL database. Things will sometimes go wrong when you use the statements.<\/p>\n","protected":false},"author":3,"featured_media":310,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[3,5],"tags":[],"class_list":["post-309","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-tutorial-how-to","category-knowledgebase"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/www.virtono.com\/community\/wp-content\/uploads\/2016\/08\/mel_banner.png?fit=546%2C293&ssl=1","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p7ISfL-4Z","jetpack_likes_enabled":true,"jetpack-related-posts":[{"id":305,"url":"https:\/\/www.virtono.com\/community\/knowledgebase\/how-mysql-and-php-work-together\/","url_meta":{"origin":309,"position":0},"title":"How MySQL and PHP Work Together","author":"Daniel Draga","date":"August 7, 2016","format":false,"excerpt":"This article is a fraction of a Number of Articles on MySQL, to access them click here. You interact with the database by passing messages to the MySQL server. The messages are composed in the SQL language, a standard computer language understood by most database management systems. 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INTRODUCTION Beneath all the cute animations, the smooth transactions, lies the ruins of the backend, and talking about websites, the backend is primarily the database. Ever wondered, how the web sites remember you?\u2026","rel":"","context":"In "Knowledgebase"","block_context":{"text":"Knowledgebase","link":"https:\/\/www.virtono.com\/community\/category\/knowledgebase\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.virtono.com\/community\/wp-content\/uploads\/2016\/08\/mysql_wallpaper_by_milesandryprower-d9o6y9z.png?fit=1024%2C576&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.virtono.com\/community\/wp-content\/uploads\/2016\/08\/mysql_wallpaper_by_milesandryprower-d9o6y9z.png?fit=1024%2C576&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.virtono.com\/community\/wp-content\/uploads\/2016\/08\/mysql_wallpaper_by_milesandryprower-d9o6y9z.png?fit=1024%2C576&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.virtono.com\/community\/wp-content\/uploads\/2016\/08\/mysql_wallpaper_by_milesandryprower-d9o6y9z.png?fit=1024%2C576&ssl=1&resize=700%2C400 2x"},"classes":[]},{"id":3746,"url":"https:\/\/www.virtono.com\/community\/tutorial-how-to\/how-to-create-a-user-and-grant-permissions-in-mysql\/","url_meta":{"origin":309,"position":2},"title":"How to create a user and grant permissions in MySQL","author":"George B.","date":"August 17, 2023","format":false,"excerpt":"Managing users is an integral part of database administration. It involves adding new users, giving them access, and, if necessary, deleting them. In this tutorial, we'll examine MySQL's user management procedure, which makes it the most widely used relational database management system available as open-source software. Creating a New User\u2026","rel":"","context":"In "Tutorials"","block_context":{"text":"Tutorials","link":"https:\/\/www.virtono.com\/community\/category\/tutorial-how-to\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.virtono.com\/community\/wp-content\/uploads\/2023\/08\/Create-a-user-and-grant-permissions-in-MySQL.png?fit=360%2C240&ssl=1&resize=350%2C200","width":350,"height":200},"classes":[]},{"id":732,"url":"https:\/\/www.virtono.com\/community\/knowledgebase\/hardening-the-defense-of-database-server\/","url_meta":{"origin":309,"position":3},"title":"Hardening the Defense of Database Server","author":"Daniel Draga","date":"November 1, 2016","format":false,"excerpt":"Importance of Database Security: Databases often store sensitive data Incorrect data or loss of data could negatively affect business operations Databases can be used as bases to attack other systems from. \u00a0 Principles of Finding Holes Don't believe the documentation Implement your own client Debug the system to understand how\u2026","rel":"","context":"In "Knowledgebase"","block_context":{"text":"Knowledgebase","link":"https:\/\/www.virtono.com\/community\/category\/knowledgebase\/"},"img":{"alt_text":"","src":"https:\/\/i0.wp.com\/www.virtono.com\/community\/wp-content\/uploads\/2016\/11\/network-security1.jpg?fit=1200%2C556&ssl=1&resize=350%2C200","width":350,"height":200,"srcset":"https:\/\/i0.wp.com\/www.virtono.com\/community\/wp-content\/uploads\/2016\/11\/network-security1.jpg?fit=1200%2C556&ssl=1&resize=350%2C200 1x, https:\/\/i0.wp.com\/www.virtono.com\/community\/wp-content\/uploads\/2016\/11\/network-security1.jpg?fit=1200%2C556&ssl=1&resize=525%2C300 1.5x, https:\/\/i0.wp.com\/www.virtono.com\/community\/wp-content\/uploads\/2016\/11\/network-security1.jpg?fit=1200%2C556&ssl=1&resize=700%2C400 2x, https:\/\/i0.wp.com\/www.virtono.com\/community\/wp-content\/uploads\/2016\/11\/network-security1.jpg?fit=1200%2C556&ssl=1&resize=1050%2C600 3x"},"classes":[]},{"id":3496,"url":"https:\/\/www.virtono.com\/community\/tutorial-how-to\/how-to-tune-your-mysql-server-for-optimal-performance\/","url_meta":{"origin":309,"position":4},"title":"How to Tune Your MySQL Server for Optimal Performance","author":"George B.","date":"June 12, 2023","format":false,"excerpt":"In this step-by-step guide, we will walk you through the process of tuning your MySQL server, helping you enhance its efficiency and responsiveness. MySQL is one of the most popular open-source relational database management systems, widely used for various applications and websites. 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