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--- en:web_development:forms:delete [2022/01/24 10:58]
mag created
+++ en:web_development:forms:delete [2023/08/16 09:33] (current)
@@ Line 71: / Line 71: @@
                     <li>
                         <label>Hero</label>
-                        <select name="hero">
+                        <select name="alias">
 <?php
     // display list of heroes
@@ Line 143: / Line 143: @@
             foreach($_POST['movie'] as $movie) {
                 if ($movie == 'new') {
-                    array_push($args, $_POST['hero'], $_POST['new_movie']);
+                    array_push($args, $_POST['alias'], $_POST['new_movie']);
                 } else {
                     error_log($movie);
                     // check if it exists already
                     $mquery = "SELECT * FROM appearances WHERE alias=? AND movie=?";
-                    $margs  = array($_POST['hero'], $movie);
+                    $margs  = array($_POST['alias'], $movie);
                     $rslt   = $pdo->prepare($mquery);
                     $rslt->execute($margs);
                     if (!$row = $rslt->fetch()) {
-                        array_push($args, $_POST['hero'], $movie);
+                        array_push($args, $_POST['alias'], $movie);
                     }
                 }
@@ Line 201: / Line 201: @@
   * Open the 'appearances' table in the 'webdev' database.
   * Select an entry and click 'Delete'.
-  * This time it won't show at the top of the screen. Instead, it shows a pop-up with
+  * This time it won't show at the top of the screen. Instead, it shows a pop-up asking for confirmation that you want to run the given query.
+  * You can see the structure of the delete query in the popup. It looks something like this.
+<code>DELETE FROM `appearances` WHERE `appearances`.`id` = 17 </code>
+  * We only need to specify the table and the details of the specific record(s) we want deleted.
+  * We don't have the 'id' in the data from the form, but we can specify the exact record using both the alias and the movie.
+==== WHERE IN ====
+  * As was the case when we were adding appearances, we can choose between deleting each movie individually or deleting a whole selection.
+  * We could identify all the checked movies like <html>(movie='Captain America' OR movie='Iron Man')</html> or we can do it more efficiently with <html>(movie IN ('Captain America', 'Iron Man')</html>. I prefer the second option.
+  * We need as many options for <html>IN</html> as we have movies, but we'll replace them with <html> ? </html> for security.
+  * Add the following code in the 'Delete Appearances' case.
+<code>            $movies = count($_POST['movie']);
+            $values = str_repeat('?,', $movies-1) . '?';
+            $query = "DELETE FROM appearances WHERE alias=? AND movie IN ($values)";</code>
+  * The first line gets the number of movies.
+  * The second line creates the string of arguments for <html>IN</html>.
+  * The third line creates the query string.
+  * Now we need to create the array of arguments.
+<code>            $args  = array($_POST['alias']);
+            foreach($_POST['movie'] as $movie) {
+                array_push($args, $movie);
+            }</code>
+  * First we create the array, then we loop through the movies and add each one to the array.
+  * Now we send the query to the database, with a check on whether it worked or not.
+<code>            $rslt = $pdo->prepare($query);
+            if ($rslt->execute($args)) {
+                $message = "$movies appearances were deleted successfully.";
+            } else {
+                $message = "There was a problem deleting $movies appearances";
+            }</code>
+  * Save and upload the code and check that everything works as expected.
+[[en:web_development:forms:javascript|Next: Javascript for Forms]]

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