php mysql modify array

In PHP development, array is a commonly used data structure. When processing data, we often need to modify the array to meet our needs. At the same time, MySQL is also a commonly used relational database management system, and we often interact with MySQL through PHP. So, how to modify data in MySQL in PHP? Let’s discuss this issue below.

1. Connect to the database

We need to connect to the MySQL database in PHP before we can modify the data in it.

First, you need to enable the mysqli extension in the php.ini file. Find the ";extension=mysqli" line of code in the php.ini file and remove the preceding semicolon.

Then, use the mysqli_connect() function to connect to the MySQL database. This function needs to pass in 4 parameters: database address, user name, password and database name. If there is a connection error, you can obtain the error information through the mysqli_connect_error() function, as shown below:

<?php
  $conn = mysqli_connect("localhost", "root", "password", "database");
  if (mysqli_connect_errno()) {
    echo "Failed to connect to MySQL: " . mysqli_connect_error();
  }
?>

2. Obtain the data that needs to be modified

Before modifying the MySQL database, you need to obtain the required data Modified data. We can use the SELECT statement to get data from the database and store it in an array in PHP. As shown below:

<?php
  $conn = mysqli_connect("localhost", "root", "password", "database");
  $result = mysqli_query($conn, "SELECT * FROM table");
  $data = array();
  while ($row = mysqli_fetch_assoc($result)) {
    $data[] = $row;
  }
?>

After the above code, the $data array obtains all the data in the table table. Now we can modify the data in it.

3. Modify data

You need to use the UPDATE statement to modify data. The UPDATE statement is used to modify existing records in the database. Its syntax is as follows:

UPDATE table_name
SET column1=value1,column2=value2,...
WHERE some_column=some_value;

Among them, table_name is the table name that needs to be modified; column1, value1, column2, value2,... are the columns and values ​​that need to be modified; the WHERE clause is used to specify the table that needs to be modified. OK. For example, to change the value of the data column in the first row of the table table to "new_data", you need to use the following code:

<?php
  $conn = mysqli_connect("localhost", "root", "password", "database");
  mysqli_query($conn, "UPDATE table SET data='new_data' WHERE id=1");
?>

After modifying the data, you can use the SELECT statement to re-obtain the latest data.

4. Modify the array

After the above operations, we have modified the data in MySQL. The results can now be stored into an array in PHP. We can use a for loop to traverse the array, find and modify the data that needs to be modified. For example, change the data field with id 1 in the $data array to "new_data", the code is as follows:

<?php
  $conn = mysqli_connect("localhost", "root", "password", "database");
  $result = mysqli_query($conn, "SELECT * FROM table");
  $data = array();
  while ($row = mysqli_fetch_assoc($result)) {
    $data[] = $row;
  }
  
  for ($i=0; $i<count($data); $i++) {
    if ($data[$i]['id']==1) {
      $data[$i]['data'] = "new_data";
      mysqli_query($conn, "UPDATE table SET data='new_data' WHERE id=1");
    }
  }
?>

In this way, the fields in the array are modified.

5. Summary

PHP and MySQL are commonly used tools in development. When processing data, arrays and databases often need to be modified. Through the above discussion, we learned how to modify arrays and MySQL. For arrays, you can use a for loop to traverse and modify the specified data; for MySQL, you can use the UPDATE statement to modify the data of the specified column. I hope the above content can help everyone process data better.

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