1. Creating databases for web applications Walk before run? Songs with features example. Retrieve information from database. Recordsets. Arrays. Loops. Homework: Get examples working. Post unique source on entity relationship diagrams or data flow diagrams OR SQL Select statement.

2. What does this do? <? $test = $_GET["test"]; $pattern = "/^\\$[0-9]$/i"; if (preg_match($pattern,$test)) { print("Entry $test passed the test"); } else { print("Entry $test failed the test"); } ?>

3. Money with commas <? $test = $_GET["test"]; print ("string to be tested is $test"); $pattern = "/^\\$[1-9][0-9]{0,2}(\,[0-9]{3})*(\.[0-9]{2})?$/"; print (" "); print ("pattern is $pattern"); print (" "); if (preg_match($pattern,$test)) { print("Entry $test passed the test"); } else { print("Entry $test failed the test"); } ?>

4. Questions? Any problems creating tables in a database –If a table with that name exists, you need to DROP TABLE ….. before creating a new one INSERT INTO…. SELECT

5. Scripts in my books example opendbo.php: required by ALL the php files createbooktable.php addbook.html, which invokes… addbook.php showbooks.php showbooksbycategory1.php, which invokes … showbooksbycategory2.php Note: need to create table and make entries for the “show” scripts to work. Questions?

6. List books in a category Pick the category you want: Choices: <?php require("opendbo.php"); $query="SELECT DISTINCT bcategory FROM books"; $categories = mysqli_query($link,$query); while ($row=mysqli_fetch_array($categories)) { $cat=$row['bcategory']; print (" $cat \n"); } mysqli_close($link); ?>

7. Show books in selected category <?php $bcat = $_GET['pickedcategory']; print "Sites in $bcat category "; require("opendbo.php"); $query="SELECT * FROM books WHERE bcategory = '$bcat' ORDER BY bdate DESC"; $result=mysqli_query($link,$query); $NoR=mysqli_num_rows($result); if ($NoR==0) { print ("No sites in that category"); }

8. else { print(" "); print(" Title Date Description "); while ($row=mysqli_fetch_array($result)) { print(" "); print(" ".$row['btitle']." "); print (" ".$row['bdate']." "); print (" ".$row['bdescription']." "); print (" "); } print (" "); } mysqli_close($link); ?>

9. Database decisions Not obvious and can be debated. I decided MAINLY to show php features to NOT have the user enter the date. I decided to NOT use ISBN for the primary key. ? Part of the course is to get practice making decisions, so, do something different!

10. Making connection A standard practice is to put the private information regarding the database in its own file, say it is called connectcode.php and then using require("opendbo.php"); –Or whatever name you choose in each program that requires connection to the database. My examples used files named connectcode.php or opendbo.php or something similar. –You will need to put in the specifics for your databases using the information sent to you. Some of my examples use $DBname. That is, the code assumes that has been set with the database name.

11. Outline of work Understand php and MySQL examples –Get your own versions working Learn [about] system design and documentation –Find and study sources on ERD and DFD –Create diagrams for a library MIDTERM Design and build enhanced versions of sample projects Propose, design, present and build your own projects

12. Advice Showing a lot of php code You will need to study it –use sources php scripts are middleware (aka server-side) –take information from html form or query string and manipulate it –often, use to compose SQL queries –take values returned from queries to compose html –Composing html and SQL makes use of php tricks such as variable names inside of quoted strings and single quotation marks inside of quoted strings

13. Advice / warning Applications involve multiple files, aka scripts. These scripts are not big! Scripts change the environment: the database, cookies –That's the whole point! So, when there is an error, you may (often) need to start all over. –Create tables –Populate –…

14. Songs with features examples http://socialsoftware.purchase.edu/jeanine.meyer/example/addsong. htmlhttp://socialsoftware.purchase.edu/jeanine.meyer/example/addsong. html –action=addsong.php http://socialsoftware.purchase.edu/jeanine.meyer/example/listsongs. phphttp://socialsoftware.purchase.edu/jeanine.meyer/example/listsongs. php http://socialsoftware.purchase.edu/jeanine.meyer/example/addfeatur e.htmlhttp://socialsoftware.purchase.edu/jeanine.meyer/example/addfeatur e.html –action=addfeature.php http://socialsoftware.purchase.edu/jeanine.meyer/example/addfeatur estosong1.phphttp://socialsoftware.purchase.edu/jeanine.meyer/example/addfeatur estosong1.php –action=addfeaturestosong2.php http://socialsoftware.purchase.edu/jeanine.meyer/example/findother s1.phphttp://socialsoftware.purchase.edu/jeanine.meyer/example/findother s1.php –action=findothers2.php Notice that in some cases, pairs are html and php and in others php and php.

15. Song database tables songs features featuresinsongs

16. Song example scripts createtables.php addsong.html and addsong.php listsongs.php addfeature.html and addfeature.php addfeaturestosong1.php and addfeaturestosong2.php findothers1.php and findothers2.php removesong1.php and removesong2.php

17. <?php function createtables($tname,$fields) { global $DBname, $link; $query = "DROP TABLE $tname"; mysqli_query($link,$query); $query="CREATE TABLE ".$tname."(".$fields.")"; if (mysqli_query($query)) { print ("The table, $tname, was created successfully. \n"); } else { print ("The table, $tname, was not created. \n"); } ?>

18. Creating movie table <?php require("opendbe.php"); $tname = "songs"; $fields = "sid INT NOT NULL AUTO_INCREMENT PRIMARY KEY, sname CHAR(50), artist CHAR(50), sdesc TEXT, syear YEAR"; createtable($tname, $fields); $tname = "features"; $fields = "fid INT NOT NULL AUTO_INCREMENT PRIMARY KEY, fname CHAR(30), fdesc TEXT"; createtable($tname, $fields); $tname = "featuresinsongs"; $fields = "fisid INT NOT NULL AUTO_INCREMENT PRIMARY KEY, fid INT NOT NULL, sid INT NOT NULL"; createtable($tname, $fields); mysqli_close($link); ?>

19. addsong.html Adding song form Song name: Artist: Song description: Year:

20. addsong.php Add song to database <?php require("opendbe.php"); $tname = "songs"; $sn=addslashes($_GET["sn"]); $sd=addslashes($_GET["sd"]); $sa=addslashes($_GET["sa"]); $sy=$_GET["sy"]; $query = "INSERT INTO $tname values ('0','$sn','$sa','$sd','$sy')"; echo $query; $result = mysqli_query($link,$query); if ($result) { print("The song was successfully added. \n"); } else { print ("The song was NOT successfully added. \n"); } ?>

21. SELECT most important, most common SQL statement. SELECT all or certain fields FROM table Soon, we get more complicated and add conditions. Sometimes conditions involves fields in more than one table.

22. listsongs.php List songs <?php require("opendbe.php"); $tname = "songs"; $query="SELECT * FROM $tname"; $result=mysqli_query($link, $query); print(" "); print(" ID Name Artist Description Year "); while ($row=mysqli_fetch_array($result)) { print(" "); print($row['sid']." "); print ($row['sname']." "); print ($row['artist']." "); print ($row['sdesc']." "); print ($row['syear']." "); print(" "); } print (" "); ?>

23. Re: features (first ERD) Add feature to the features table Then add the fact that a specific song has that feature to the featuresinsongs table. songs sid sn artist sdesc syear features fid fname fdesc featuresinsongs fisid fid sid

24. addfeature.html Adding feature form Feature name: Feature description:

25. addfeature.php Add feature to database <?php require("opendbe.php"); $tname = "features"; $fn=$_GET["fn"]; $fd=$_GET["fd"]; $query = "INSERT INTO $tname values ('0','".$fn."', '".$fd."')"; $result = mysqli_query($link,$query); if ($result) { print("The feature was successfully added. \n"); } else { print ("The feature was NOT successfully added. \n"); } ?>

26. Comments The opendbe.php has database name and password. It sets $link used later. NOTE: trick of php that variable names inside double quotes get evaluated. NOTE: the presence of the single quotes around strings. These are required by MySQL (and other DBMS) Code needs to be improved: What if name or description had quotes or slashes? Try it and then add $desc =addslashes($desc);

27. True story This happens to me, more than once. When copying over an example with song titles, tried to input You're the one Did not work! Need to 'escape' the quotation mark (aka apostrophe).

28. Comments [Go over this again next class] Put the db connection code in separate file, to be included in all other files The fields are extracted by name. –Chose not to extract and display mid The $rs produced by the SELECT query is called a recordset. It is like a table. Its rows can be extracted one at a time.

29. More SQL ALTER: this is for changing or adding a field definition –This also can be done in phpmyadmin DROP: this is dropping a table. This is good to do before creating a table, just in case you already did it OR don't drop it, and check for errors.

30. Caution My songs with features database may contain nonsense entries Also, no provision for duplicates or near duplicates…

31. Another true story When I checked the findothers1.php and findothers2.php, it didn't seem to be working… BECAUSE I had put in only a limited number of features and no feature was shared by more than one song!

32. Remove application Need to remove song PLUS all the feature/song records http://socialsoftware.purchase.edu/jeanine. meyer/example/removesong1.phphttp://socialsoftware.purchase.edu/jeanine. meyer/example/removesong1.php

33. from removesong1.php Select a song to be deleted with its features <?php require("opendbe.php"); $query="Select * from songs"; $result=mysqli_query($link, $query); while ($row=mysqli_fetch_array($result)) { print(" "); print ($row['sname']. " ". $row['artist']." ".$row['sdesc']." ".$row['syear']." "); } ?>

34. from removesong2.php <?php require("opendbe.php"); $sid=$_GET["song"]; $query = "Delete from songs where sid='$sid' limit 1"; print ($query); $result = mysqli_query($link,$query); if ($result) { print("The song $sid was deleted. \n"); } else { print ("The song $sid was not deleted. \n"); } $query = "Delete from featuresinsongs where sid='$sid'"; $result = mysqli_query($link,$query); if ($result) { print("The features for song $sid were deleted. \n"); } else { print ("The features for song $sid were NOT successfully added. \n"); } ?>

35. Notes The bad results let me know that I had the name of the tables wrong! – song for songs – featuresinsong for featuresinsongs

36. Who are the agents? In existing find similar songs applications, the assigning of features may not be an end user function….. In a general application, for the public, should have more security. Don't let people remove songs…. MUCH more important, don't let people create the tables again.

37. Continue with song example Recall 3 tables –songs –features –featuresinsongs Previously, showed adding songs and adding features. Now want to provide way to add a feature to a song DEMONSTRATE Select a song and find all songs that share at least one feature with the selected song DEMONSTRATE

39. Notice Since the form will make use of check box, the information passed needs to be an array.

40. from addfeaturestosong1.php <?php require("opendbe.php"); $query="Select * from songs"; $result=mysqli_query($link, $query); while ($row=mysqli_fetch_array($result)) { print(" "); print ($row['sname']." ".$row['artist']." ".$row['sdesc']." ".$row['syear']." ");} ?>

41. <?php $query="Select * from features"; $result=mysqli_query($link, $query); while ($row=mysqli_fetch_array($result)) { print(" "); print ($row['fname']." ".$row['fdesc']." "); } ?>

42. from addfeaturestosong2.php <?php require("opendbe.php"); $tname = "featuresinsongs"; $sid=$_GET["song"]; $ft=$_GET["ft"]; for($i=0; $i < count($ft); $i++) { $fid=$ft[$i]; $query = "INSERT INTO $tname SET fid='$fid', sid='$sid'"; $result = mysqli_query($link,$query); if ($result) { print("The song $sid had feature $fit successfully added. \n"); } else { print ("The song $sid had feature $fit NOT successfully added. \n"); } } ?>

43. Your database In the ReadMe file on your [regular] students.purchase.edu account, there was information for your socialsoftware.purchase.edu (FA2011) database –name, –database name –password In the following example, WKILLORAN is the name, WKILLORAN_DB is the database name and PASSWORD is the password. The host (held in $host) is a special virtual server set up for us. SUBSTITUTE FROM THE EMAIL SENT TO YOU!

44. example of a fake connect file <?php $host = '127.0.0.1'; $link = mysqli_connect($host, 'WKILLORAN', 'PASSWORD'); if (!$link) { die('Not connected : '. mysql_error()); } if (!mysqli_select_db('WKILLORAN_DB', $link)) { echo 'Could not select database'; exit; } $DBname = 'WKILLORAN_DB'; ?>

45. MySQL queries ALL return something! This can be indication of success or a pointer to array (like) object holding data php has built-in commands for interactions with MySQL. NOTE: also has commands for generic DBMS –EXTRA CREDIT opportunity to report on php and other DBMS or report on comparisons.

46. Extra credit Report on Ruby on Rails Groovy ??

47. SELECT overview Extract some or all fields in table(s) –Also operations: COUNT, SUM, AVG Set conditions on which records by expression involving fields in one or more tables –WHERE, JOIN … ON Aggregate GROUP records Set conditions on the aggregated data HAVING Set LIMITS

48. Basic $query="SELECT * FROM movies"; Could have used $query ="SELECT mname, mdesc, myear FROM movies"; –Since I suggested not displaying the mid field Use $mysqli_fetch_array to extract a row. This is an associative array that represents the constructed record of the selected data The results of $mysqli_fetch_array can be used as a condition. When it fails, there were no more rows.

49. Performance how much time is taken by an SQL statement and/or php code This can be significant, that is, amount to something significant in large databases. DBMS have tools to determine this and you also can experiment.

50. Looping $query="SELECT * FROM movies"; $rs=mysqli_query( $link,$query); while ($row=mysqli_fetch_array($rs)){ print($row['mname']. " (".$row['myear']. "): "); print($row['mdesc']); print(" "); }

51. What looping does Builds up a [long] string of html in this case (string encoded using my own design in the video clip archive case) Use the concatenate operator. Note [those pesky] single quotation marks –For the indexing into the associative array that is the row of data –For the attribute values in the html

52. Caution / Encouragement SELECT statements can be equivalent to many lines of code So Give yourself time to understand and create the statements. You do not have to do it the shortest way and/or only one statement. This may not even be the most efficient. Build up $query in stages (using.) and use print ("The query is $query");

53. Comments The AS t and AS v allow you to use a shorter name in referencing the fields. Remember that equality condition in SQL is one equal sign. Remember to use single quotation marks around strings. –If $tag is a variable holding a string, the SQL statement needs the quotation marks! The 'sent back' data is itself encoded as a comma separated list of clip addresses and clip titles

54. GROUP HAVING SQL can aggregate (GROUP) records SQL can accept a condition applied to the GROUPs –The WHERE and the JOIN ON apply to the individual records GROUP generally is applied using aggregate functions, such as SUM, COUNT, AVG, MIN, MAX

55. Question Assume a table of student information, including major, gpa, credits What are the majors that have the highest averages among their students AND let's just consider juniors and seniors? –Define junior and senior as having more than 60 credits This is our operational definition. It can be a challenge to make these definitions. –Display the top 3 majors along with their average GPA

56. SELECT example SELECT department, AVG(gpa) FROM student_info WHERE credits >60 GROUP BY department HAVING AVG(gpa) > 3 ORDER BY AVG(gpa) DESC LIMIT 3 Select student records that have more than 60 credits. Group by common department. Take an average over the gpa fields. Just select those groups (that is, departments) where the average is over 3 (over B). Order from highest to lowest. Just take the first (top) 3.

57. Select example from songs with features $sid is the id of a selected song SELECT sname, COUNT(*) as c FROM featuresinsongs AS f1, songs AS s, featuresinsongs AS f2 WHERE f1.sid='$sid' AND f1.fid=f2.fid AND f2.sid!='$sid' AND s.sid=f2.sid GROUP BY sname ORDER BY c DESC, sname The featuresinsongs table has song id field and feature id field. The name of a song is in the songs table. Select all the song and feature records that have features in common with features possessed by $sid. But don't select any song/feature row in which the song id IS $sid. Group by sname. Order from biggest to smallest.

58. findothers1.php <?php require("opendbe.php"); $query=”SELECT * FROM songs"; $result=mysqli_query($link, $query); while ($row=mysqli_fetch_array($result)) { print(" "); print ($row['sname']." ".$row['artist']." ". $row['sdesc']." ".$row['syear']." "); } ?>

59. from findothers2.php <?php require("opendbe.php"); $tname = "featuresinsongs"; $sid=$_GET["song"]; $query="SELECT sname, COUNT(*) AS c FROM featuresinsongs AS f1, songs AS s, "; $query.="featuresinsongs AS f2 WHERE f1.sid='$sid' "; $query.="AND f1.fid=f2.fid "; $query.="AND f2.sid!='$sid' "; $query.="AND s.sid=f2.sid GROUP BY sname ORDER BY c DESC, sname";

60. $result=mysqli_db_query($DBname, $query, $link); $nr = mysqli_num_rows($result); if ($nr<1) { print ("Sorry, no feature match for that song."); } else { print(" "); while ($row=mysqli_fetch_array($result)) { print(" "); print(" ".$row['sname']." "); print ($row['c']." "); } } ?>

61. 3-tier model Database (MySQL data) holds the information. The middleware (php) is the application of the business decisions. The HTML (with JavaScript) program handles the interactions with people, including the presentation of results. Reflect on this in terms of examples.

62. Motivation for Diagrams Diagrams are tools for the design stage and for documentation. Databases that are more than one table are represented by Entity Relationship Diagrams. Applications (using databases or not) are represented by Data Flow diagrams. Database applications typically involve many small[er] files/programs/scripts. The exact structure of the diagrams less important than using some type of representation. Focus on this next class.

63. Homework Keep practicing with php and MySQL. Making additions/enhancements/changes to the songs project is a possibility for the next project. Find, review, and post reference and comments on unique source for Entity Relationship Diagrams and/or Data Flow Diagrams OR the Select statement in SQL.