Introduction To Lamp P2

Muhammad Abdur Rahman AdnaN jhoroTEK.com [email_address]

COMP519: Web Programming (University of Liverpool)

http://www.csc.liv.ac.uk/~martin/teaching/comp519/

http://www.w3schools.com

SQL stands for Structured Query Language

using SQL can you can

access a database

execute queries , and retrieve data

insert, delete and update records

SQL works with database programs like MS Access, DB2, Informix, MS SQL Server, Oracle, Sybase, mySQL, Postgre etc.

A database most often contains one or more tables. Each table is identified by a name (e.g. "Customers" or "Orders"). Tables contain records (rows) with data.

The table above contains two records (one for each blog) and four columns For example, a table called “ Blog ": Id Title Body Publish_date 1 Good morning How are you today? 2008-02-22 08:10:00 2 Good night How was your day? 2008-02-22 18:25:00

With SQL, you can query a database and have a result set returned.

A query like this: SELECT title FROM blog ; Gives a result set like this: The mySQL database system requires a semicolon at the end of the SQL statement! Title Good morning Good night

The Data Definition Language (DDL) part of SQL permits database tables to be created or deleted :

CREATE TABLE

ALTER TABLE

DROP TABLE

The query and update commands together form the Data Manipulation Language (DML) part of SQL :

SELECT

UPDATE

DELETE

INSERT INTO

*Here we will use some of them in mySQL

You can log into our mySQL server from Linux by typing in the prompt

From here you can create and drop tables, and modify the data in your tables. But first, you must specify which database on the server you want to use. bash-2.05b$ mysql -u root Welcome to the MySQL monitor. Commands end with ; or g. Your MySQL connection id is 209201 to server version: 5.0.22 Type 'help;' or 'h' for help. Type 'c' to clear the buffer. mysql> mysql> use myDatabase; Database changed

Next, you can create the table you will be using for the upcoming project. For example,

mysql> CREATE TABLE blog ( -> id INT NOT NULL AUTO_INCREMENT, -> title VARCHAR(48), -> body VARCHAR(48), -> publish_date DATETIME, -> PRIMARY KEY(id)); Hit Enter after each line (if you want). MySQL doesn’t try to interpret the command itself until it sees a semicolon ( ; ) Query OK, 0 rows affected (0.02 sec) *If the server gives you a big ERROR, just try again from the top!

Using DESCRIBE you can see the structure of a table

Using INSERT INTO you can insert a new row into your table. For example,

mysql> INSERT INTO blog -> VALUES( ‘’ , ’Good Afternoon’ , ’Had your Lunch’ , NOW() ); Query OK, 1 row affected (0.00 sec) Using SELECT FROM you select some data from a table. mysql> SELECT * FROM blog ; +-----+---------+--------+------------+----------------------+ | id | title | body | publish_date | +-----+---------+--------+------------+----------------------+ | 1 | Good Afternoon | Had your Lunch | 2008-02-22 12:20:20 | +-----+---------+--------+------------+----------------------+ 1 row in set (0.00 sec)

You can repeat inserting until all data is entered into the table.

The SELECT command is the main way of getting data out of a table, or set of tables.

SELECT * FROM blog ;

Here the asterisk means to select (i.e. return the information in) all columns.

You can specify one or more columns of data that you like, such as

SELECT title, body FROM blog ;

+-------------+--------+

| title | body |

+-------------+--------+

| Good Afternoon | Had your Lunch |

| How are you? | Doing fine? |

+---------+--------+

2 rows in set (0.00 sec)

You can specify other information that you want in the query using the WHERE clause.

SELECT * FROM blog WHERE id=‘2’ ;

+-----+---------+--------+------------+----------------------+

| num | title | body | publish_date |

+-----+---------+--------+------------+----------------------+

| 2 | Good Afternoon |Had your Lunch | 2008-02-22 12:20:20 |

+-----+---------+--------+------------+----------------------+

1 row in set (0.00 sec)

The UPDATE statement is used to modify the data in a table.

The DELETE statement is used to delete rows in a table.

SHOW tables; gives a list of tables that have been defined in the database

ALTER TABLE blog DROP publish_date ; would drop the “publish_date” column from all records

DROP TABLE blog ; deletes the entire “blog” table, and its definition (use the DROP command with extreme care!!)

DELETE FROM blog ; removes all rows from the “blog” table (so once again, use the DELETE command with great caution), the table definition remains to be used again

A more useful(?) command is something like

DELETE FROM blog WHERE (id > 5) AND (id <= 10);

which selectively deletes blog based on their “id” values (for example).

HELP; gives the SQL help

HELP DROP; gives help on the DROP command, etc.

We can simply use PHP functions and mySQL queries together:

Host: localhost

Database: bdosdn

Username: root

Password: <blank>

Connect to the database server and login

mysql_connect( " host "," username "," password " );

Choose the database

mysql_select_db( " database " );

Send SQL queries to the server to add, delete, and modify data

mysql_query( " query " );

Close the connection to the database server

mysql_close();

<html>

<head>

<title>Putting Data in the DB</title>

</head>

<body>

<?php

/*insert blogs into DB*/

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

$db = mysql_connect("localhost", "root", "root") or die('DB connection error!');

mysql_select_db("bdosdn");

$date=date("Y-m-d"); /* Get the current date in the right SQL format */

$sql="INSERT INTO blog VALUES('','" . $_POST["title"] . "','" . $_POST["body"] . "', NOW())"; /* construct the query */

mysql_query($sql);

mysql_close();

echo"<h3>Thank you. The data has been entered.</h3> ";

echo'<p><a href="blog_entry.php">Back to post</a></p>' . " ";

echo'<p><a href="blog_view.php ">View the blog lists</a></p>' ." ";

}

Blog_entry.php

else {

?>

<h3>Enter your blog post into the database</h3>

<form action="blog_entry.php" method="POST">

Title: <input type="text" name="title" /> <br/>

Body: <input type="textarea" name="body" /> <br/>

<input type="submit" name="submit" /> <input type="reset" />

</form>

<?php

}

?>

</body>

</html>

Blog_entry.php

Similarly, we can get some information from a database:

Connect to the server and login, choose a database

mysql_connect( " host "," username "," password " );

mysql_select_db( " database " );

Send an SQL query to the server to select data from the database into an array

$result =mysql_query( " query " );

Either, look into a row and a fieldname

$num =mysql_numrows( $result );

$variable =mysql_result( $result , $i ," fieldname " );

Or, fetch rows one by one

$row =mysql_fetch_array( $result );

Close the connection to the database server

mysql_close();

<html> <head> <title>Getting Data out of the DB</title> </head> <body> <h1> Blog Database </h1> <?php /*get blog from the DB */ $db = mysql_connect("localhost", "root", "root") or die('DB connection error!'); mysql_select_db("bdosdn", $db); $sql = "SELECT * FROM blog ORDER BY id desc"; $result=mysql_query($sql); while($row=mysql_fetch_array($result)){ echo "<h4> Title: " . $row["title"] . "</h4> "; echo "<h5> Publish Date: " . $row["publish_date"] . "<br/> Body: " . $row["body"] . "</h5> "; echo '<hr>'; } mysql_close(); ?> </body> </html> Blog_view.php