Web Code Addict: Query

Tuesday, April 11, 2023

MYSQL 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 Using a PHP Script

You can use the SQL DELETE command with or without the WHERE CLAUSE into the PHP function – mysql_query(). This function will execute the SQL command in the same way as it is executed at the mysql> prompt.

Example

Try the following example to delete a record from the tutorial_tbl whose tutorial_id is 3.

<?php
   $dbhost = 'localhost';
   $dbuser = 'root';
   $dbpass = '';
   $conn = mysql_connect($dbhost, $dbuser, $dbpass);
   
   if(! $conn ) {
      die('Could not connect: ' . mysql_error());
   }

   $sql = 'DELETE FROM tutorials_tbl WHERE tutorial_id = 3';

   mysql_select_db('TUTORIALS');
   $retval = mysql_query( $sql, $conn );

   if(! $retval ) {
      die('Could not delete data: ' . mysql_error());
   }
   echo "Deleted data successfully\n";
   mysql_close($conn);
?>

Monday, April 3, 2023

Data Insertion in MYSQL

To insert data into a MySQL table, you would need to use the SQL INSERT INTO command.

You can insert data into the MySQL table by using the mysql> prompt or by using any script like PHP.

Here are some syntax rules to follow:

The SQL query must be quoted in PHP

String values inside the SQL query must be quoted

Numeric values must not be quoted

The word NULL must not be quoted

Syntax

INSERT INTO `table_name`(column_1,column_2,...) VALUES (value_1,value_2,...);

INSERT INTO `table_name` is the command that tells MySQL server to add new row into a table named `table_name`.

(column_1,column_2,...) specifies the columns to be updated in the new row

VALUES (value_1,value_2,...) specifies the values to be added into the new row

String data types - all the string values should be enclosed in single quotes.

Numeric data types - all numeric values should be supplied directly without enclosing them in single
or double quotes.

Date data types - enclose date values in single quotes in the format 'YYYY-MM-DD'.

Inserting Data Using a PHP Script
Example

When supplying the data values to be inserted into the new table, the following should be considered while

dealing with different data types.

You can use the same SQL INSERT INTO command into the PHP function mysql_query() to

insert data into a MySQL table.

This example will take three parameters from the user and will insert them into the MySQL

table −

<html>

   <head>
      <title>Add New Record in MySQL Database</title>
   </head>

   <body>
      <?php
         if(isset($_POST['add'])) {
            $dbhost = 'localhost';
            $dbuser = 'root';
            $dbpass = 'rootpassword';
            $conn = mysql_connect($dbhost, $dbuser, $dbpass);
         
            if(! $conn ) {
               die('Could not connect: ' . mysql_error());
            }

            if(! get_magic_quotes_gpc() ) {
               $tutorial_title = addslashes ($_POST['tutorial_title']);
               $tutorial_author = addslashes ($_POST['tutorial_author']);
            } else {
               $tutorial_title = $_POST['tutorial_title'];
               $tutorial_author = $_POST['tutorial_author'];
            }

            $submission_date = $_POST['submission_date'];
   
            $sql = "INSERT INTO tutorials_tbl ".
               "(tutorial_title,tutorial_author, submission_date) "."VALUES ".
               "('$tutorial_title','$tutorial_author','$submission_date')";
               mysql_select_db('TUTORIALS');
            $retval = mysql_query( $sql, $conn );
         
            if(! $retval ) {
               die('Could not enter data: ' . mysql_error());
            }
         
            echo "Entered data successfully\n";
            mysql_close($conn);
         } else {
      ?>
   
      <form method = "post" action = "<?php $_PHP_SELF ?>">
         <table width = "600" border = "0" cellspacing = "1" cellpadding = "2">
            <tr>
               <td width = "250">Tutorial Title</td>
               <td>
                  <input name = "tutorial_title" type = "text" id = "tutorial_title">
               </td>
            </tr>
         
            <tr>
               <td width = "250">Tutorial Author</td>
               <td>
                  <input name = "tutorial_author" type = "text" id = "tutorial_author">
               </td>
            </tr>
         
            <tr>
               <td width = "250">Submission Date [   yyyy-mm-dd ]</td>
               <td>
                  <input name = "submission_date" type = "text" id = "submission_date">
               </td>
            </tr>
      
            <tr>
               <td width = "250"> </td>
               <td> </td>
            </tr>
         
            <tr>
               <td width = "250"> </td>
               <td>
                  <input name = "add" type = "submit" id = "add"  value = "Add Tutorial">
               </td>
            </tr>
         </table>
      </form>
   <?php
      }
   ?>
   </body>
</html>

Pages

Tuesday, April 11, 2023

MYSQL Delete Query

Syntax

Deleting Data Using a PHP Script

Example

Monday, April 3, 2023

Data Insertion in MYSQL

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