mysqli

Khóa học miễn phí MySQLi – Delete Query nhận dự án làm có lương

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MySQLi – Delete Query

If you want to delete a record from any MySQL table, then you can use the SQL command DELETE FROM. You can use this command at the mysql> prompt as well as in any script like PHP.

Syntax

The following code block has a generic SQL syntax of the DELETE command to delete data from a MySQL table.

DELETE FROM table_name [WHERE Clause]

  • If the WHERE clause is not specified, then all the records will be deleted from the given MySQL table.

  • You can specify any condition using the WHERE clause.

  • You can delete records in a single table at a time.

The WHERE clause is very useful when you want to delete selected rows in a table.

Deleting Data from the Command Prompt

This will use the SQL DELETE command with the WHERE clause to delete selected data into the MySQL table – tutorials_tbl.

Example

The following example will delete a record from the tutorial_tbl whose tutorial_id is 3.

root@host# mysql -u root -p password;
Enter password:*******

mysql> use TUTORIALS;
Database changed

mysql> DELETE FROM tutorials_tbl WHERE tutorial_id=3;
Query OK, 1 row affected (0.23 sec)

mysql>

Deleting Data Using a PHP Script

PHP uses mysqli query() or mysql_query() function to delete records in a MySQL table. This function takes two parameters and returns TRUE on success or FALSE on failure.

Syntax

$mysqli→query($sql,$resultmode)

Sr.No. Parameter & Description
1

$sql

Required – SQL query to delete records in a MySQL table.
2

$resultmode

Optional – Either the constant MYSQLI_USE_RESULT or MYSQLI_STORE_RESULT depending on the desired behavior. By default, MYSQLI_STORE_RESULT is used.

Example

Try the following example to delete a record in a table −

Copy and paste the following example as mysql_example.php −

<html>
   <head>
      <title>Deleting MySQL Table record</title>
   </head>
   <body>
      <?php
         $dbhost = ''localhost
         $dbuser = ''root
         $dbpass = ''root@123
         $dbname = ''TUTORIALS
         $mysqli = new mysqli($dbhost, $dbuser, $dbpass, $dbname);
         
         if($mysqli→connect_errno ) {
            printf("Connect failed: %s<br />", $mysqli→connect_error);
            exit();
         }
         printf(''Connected successfully.<br />'');
		 
         if ($mysqli→query(''DELETE FROM tutorials_tbl where tutorial_id = 4'')) {
            printf("Table tutorials_tbl record deleted successfully.<br />");
         }
         if ($mysqli→errno) {
            printf("Could not delete record from table: %s<br />", $mysqli→error);
         }
   
         $sql = "SELECT tutorial_id, tutorial_title, tutorial_author, submission_date FROM tutorials_tbl";
		 
         $result = $mysqli→query($sql);
           
         if ($result→num_rows > 0) {
            while($row = $result→fetch_assoc()) {
               printf("Id: %s, Title: %s, Author: %s, Date: %d <br />", 
                  $row["tutorial_id"], 
                  $row["tutorial_title"], 
                  $row["tutorial_author"],
                  $row["submission_date"]);               
            }
         } else {
            printf(''No record found.<br />'');
         }
         mysqli_free_result($result);
         $mysqli→close();
      ?>
   </body>
</html>

Output

Access the mysql_example.php deployed on apache web server and verify the output. Here we”ve entered multiple records in the table before running the select script.

Connected successfully.
Table tutorials_tbl record deleted successfully.
Id: 1, Title: MySQL Tutorial, Author: Mahesh, Date: 2021
Id: 2, Title: HTML Tutorial, Author: Mahesh, Date: 2021
Id: 3, Title: PHP Tutorial, Author: Mahesh, Date: 2021
Id: 5, Title: Apache Tutorial, Author: Suresh, Date: 2021

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