使用PHP MySQL的文本版本控制系统

I am trying to create a system where a user can enter some text and another user can edit that input and another can edit the input that the second user has entered. This is the code that I have so far; it only works as a reply system to a post at the moment:

<?php
    include 'includes/connection.php';

    $query = "SELECT * FROM branches";  
    $result1 = mysql_query($query) or die(mysql_error());

    while($person = mysql_fetch_array($result1)) {  //As long as there is data, output the data
        $id = $person['ID'];
        $query2 = "SELECT * FROM branchesedit WHERE (parent_id = '$id' )";
        $result2 =  mysql_query($query2) or die(mysql_error());

        echo "<h3>" . $person['Names'] . "</h3>";
        echo "<p>" . $person['Lyrics'] . "</p>";
        echo "<a href=\"modify.php?id=" . $person['ID'] . "\">Modify Song</a>";
        echo "<span> </span>";
        echo "<a href=\"delete.php?id=" . $person['ID'] . "\">Delete Song</a>"; 

        while($row2 = mysql_fetch_array($result2)){
            echo "<h3>" . $row2['Name'] . "</h3>";
            echo "<p>" . $row2['LyricUpdate'] . "</p>";
        }
    }
?>

modify.php

<?php
    if(isset($_POST['submit'])) {
        $query = "SELECT ID FROM branches WHERE ID = $_GET[id]";

        mysql_query("INSERT into branchesedit(`IDs`, `Name`, `LyricUpdate`, `parent_id`)
            VALUES ('','$_POST[inputName]', '$_POST[ta]', '$_POST[id]')") or die(mysql_error());

        echo "Song has been modified";
        header("Location: index.php");  
    }
?>

Note:

• You are using an isset() function on your modify.php where in your first given code (guessing your index.php) does not have a submit button. Only has a link that will redirect users to modify.php.
• Better include a connection in your modify.php to establish connection so you can run your query.
• You should consider using mysqli_* prepared statement rather than the deprecated mysql_* functions to prevent SQL injections.

Your modify.php in prepared statement:

<?php
    /* INCLUDE HERE YOUR CONNECTION */
    if(!empty($_GET['id'])) {

      if($stmt = $con->prepare("SELECT IDs, Name, LyricUpdate FROM branchesedit WHERE parent_id = ? ORDER BY IDs DESC")){
        $stmt->bind_param("i",$_GET["id"]);
        $stmt->execute();
        $stmt->store_result();
        $stmt->bind_result($id,$name,$lyricupdate);
        $stmt->fetch();
        ?>
          <h1>Modified by: <?php echo $name; ?></h1>
          <form action="modify.php" method="POST">
            <input type="hidden" name="id" value="<?php echo $_GET["id"]; ?>">
            <input type="text" name="inputName" value="<?php echo $name; ?>"><br>
            <textarea name="ta"><?php echo $lyricupdate; ?>"></textarea><br>
            <input type="submit" name="submit">
          </form>
        <?php
        $stmt->close();
      } /* END OF PREPARED STATEMENT */
    } /* END OF NOT EMPTY ID */

    if(isset($_POST["submit"])){

      if($stmt = $con->prepare("INSERT into branchesedit (`Name`, `LyricUpdate`, `parent_id`)
        VALUES (?,?,?)")){
        $stmt->bind_param("ssi",$_POST["inputName"],$_POST["ta"],$_POST["id"]);
        $stmt->execute();
        $stmt->close();
      } /* END OF INSERT PREPARED STATEMENT */

      echo "Song has been modified";
      header("LOCATION: index.php");  
    } /* END OF ISSET SUBMIT */
?>

Summary:

• When a user clicks on Modify Song link, user will be redirected to modify.php and then runs a query that will select the latest edit from your table branchesedit based from the ID being passed from the link.
• User will see a form that is already filled up based from the last edit.
• When submitted, it will still be in the modify.php and then runs an insert query.
• After the insert query, it will redirect back to index.php
• Replace the necessary connection variable I used in the prepared statement:

Example of your connection to be included in your queries (connection.php):

$con = new mysqli("Yourhost", "Yourusername", "Yourpassword", "Yourdatabase");

/* CHECK CONNECTION */
if (mysqli_connect_errno()) {
    printf("Connect failed: %s
", mysqli_connect_error());
    exit();
}