If Only. More SQL and PHP

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Harvey Blake
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1 If Only More SQL and PHP

2 PHP: The if construct If only I could conditionally select PHP statements to execute. That way, I could have certain actions happen only under certain circumstances The if statement tells PHP to execute a set of statements only if some condition is met.

4 Basic If Syntax If (condition) { conditional code to be executed when condition is true }

5 Simple if Statement <?php if ($a > $b) echo "a is bigger than b";?>

6 Not So Simple if Statement if (isset($_get[ addartist ])) { include form.html.php ; exit(); }

7 Not So Simple if Statement if (isset($_get[ addartist ])) { include form.html.php ; exit(); }

8 $_GET and the HTML GET HTML GET: Sends data by tacking it onto the url $_GET: A predefined PHP associative array of variables passed to the current script via the URL.

9 Not So Simple if Statement if (isset($_get[ addartist ])) { include form.html.php ; exit(); }

10 $_POST and the HTML POST HTML POST method used in forms to capture data entered on the form $_POST A predefined PHP associative array of variables that holds data from the form that was passed to it by the HTML POST method.

11 HTML POST Method Example HTML POST Example (form.html.php): <body> <form action="?" method="post"> <div> <label for= artist_name">type a new artist here:</label> <textarea id= artist_name" name="artist_name" rows="3" cols="40"> </textarea> </div> <div><input type="submit" value="add"></div> </form>

12 PHP $_POST in an if Statement if(isset($_post['artist_name'])) { $sql = 'INSERT INTO artist SET artist_name = :artist_name'; $s = $pdo->prepare($sql); $s->bindvalue(':artist_name', $_POST['artist_name']); $s->execute(); header('location:.'); exit(); }

13 PHP $_POST in an if Statement if(isset($_post['artist_name'])) { $sql = 'INSERT INTO artist SET artist_name = :artist_name'; $s = $pdo->prepare($sql); $s->bindvalue(':artist_name', $_POST['artist_name']); $s->execute(); header('location:.'); exit(); }

14 PHP $_POST in an if Statement if(isset($_post['artist_name'])) { $sql = 'INSERT INTO artist SET artist_name = :artist_name'; $s = $pdo->prepare($sql); $s->bindvalue(':artist_name', $_POST['artist_name']); $s->execute(); header('location:.'); exit(); }

15 PHP $_POST in an if Statement if(isset($_post['artist_name'])) { $sql = 'INSERT INTO artist SET artist_name = :artist_name'; $s = $pdo->prepare($sql); $s->bindvalue(':artist_name', $_POST['artist_name']); $s->execute(); header('location:.'); exit(); }

16 No Primary Key? Let s go back to that INSERT statement: INSERT INTO artist SET artist_name = :artist_name Notice that only the artist name is set for this new row. There is no value specified for the primary key column: artist_id! Default value for artist_id is 0 For the music database artist table (the way it is currently created), this statement would insert a new row with the artist_id = 0

17 AUTO_INCREMENT We need MySQL to figure that out for us and assign a new row the next available primary key value for us. To get MySQL to do this for us, there are two options: include the AUTO_INCREMENT functionality for a column as part of the table definition when we create the table. modify the table to add the AUTO_INCREMENT functionality for a column.

18 USING ALTER TABLE ALTER TABLE table_name MODIFY COLUMN column_name data_type NOT NULL AUTO_INCREMENT;

19 Example ALTER TABLE artist MODIFY COLUMN artist_id INT NOT NULL AUTO_INCREMENT;

20 SHOW CREATE TABLE album;

21 DELETE Index.php if(isset($_get[ 'deleteartist' ])) { $sql='delete FROM artist WHERE artist_id = :artist_id'; $s=$pdo->prepare($sql); $s->bindvalue(':artist_id', $_POST['artist_id']); $s->execute(); header('location:.'); exit(); }

22 DELETE if(isset($_get[ 'deleteartist' ])) { $sql='delete FROM artist WHERE artist_id = :artist_id'; $s=$pdo->prepare($sql); $s->bindvalue(':artist_id', $_POST['artist_id']); $s->execute(); header('location:.'); exit(); }

23 DELETE if(isset($_get[ 'deleteartist' ])) { $sql='delete FROM artist WHERE artist_id = :artist_id'; $s=$pdo->prepare($sql); $s->bindvalue(':artist_id', $_POST['artist_id']); $s->execute(); header('location:.'); exit(); }

24 Which Row to Delete? output.html.php <body> <p><a href="?addartist">add an artist</a></p> <p> <em>here are the artists</em></p> <?php foreach ($artists as $art):?> <form action="?deleteartist" method="post"> <p> <?php echo $art;?> <input type="hidden" name="artist_id" value="<?php echo $artist['artist_id'];?>" > <input type="submit" value="delete"> </p> </form> <?php endforeach;?> </p> </body>

25 Which Row to Delete? output.html.php <body> <p><a href="?addartist">add an artist</a></p> <p> <em>here are the artists</em></p> <?php foreach ($artists as $art):?> <form action="?deleteartist" method="post"> <p> <?php echo $art;?> <input type="hidden" name="artist_id" value="<?php echo $artist['artist_id'];?>" > <input type="submit" value="delete"> </p> </form> <?php endforeach;?> </p> </body>

CSCI-UA: Database Design & Web Implementation. Professor Evan Sandhaus

CSCI-UA: Database Design & Web Implementation. Professor Evan Sandhaus CSCI-UA:0060-02 Database Design & Web Implementation Professor Evan Sandhaus sandhaus@cs.nyu.edu evan@nytimes.com Lecture #10: Open Office Base, Life on the Console, MySQL Database Design and Web Implementation