Accessing mySQL relational database

MySQL database.

Today, we will attempt and open a connection to the MySQL server.

We need to specify the databaseIssue queries (no updates at this stage)display the results.Close the connection.

Connecting to the MySQL Server

To connect to a MySQL server, you need to invoke the mysql_connect() function.

Here is a typical use of the function:$db = mysql_connect("localhost", "userName", "password");

if (!($db))

die("Failed to connect to database server");

If mysql_connect() fail to open the database, then $db is set to false.

Once connected!

Once connected, you need to select the database using the mysql_select_db() function.

Here is a typical use of the function:$dbOK = mysql_select_db("testdb");

if (!($dbOK))

die("Failed to access database");

Similarly if mysql_select_db() fail to access the database, then $dbOK is set to false.

Lets start with simple SELECT

You know SQL commands in your database class. Now is the time to use it. Suppose you want to list all the attributes of the employee table.

select * from employee

In MySQL you would do the following:$query = "SELECT * FROM employee";$result = mysql_query($query);

if (mysql_error()) {

die("cannot processed select query");}

$num = mysql_num_rows($result);

Displaying the results or sometimes call Resultsets Previously you were able to know the number of rows. If you

know the attribute names, $num = mysql_num_rows($result); // from before$counter = 0;if ($num > 0) {

while ($counter < $num) {echo mysql_result($result, $counter, "emp_id");echo " ";echo mysql_result($result, $counter, "address");echo "<br />";$counter++;

}}else {

echo "No rows found";}mysql_free_result($result); // it is good to free memorymysql_close(); // close the database

Alternatively, you can use this way

$num = mysql_num_rows($result); // from before

if ($num > 0) {while ($row = mysql_fetch_assoc($result)) {

echo $row['emp_id'];echo " ";echo $row['address'];echo “<br />";

}}else {

echo "No rows found"; }mysql_free_result($result); // it is good to free memorymysql_close(); // close the database

pex5.php, pex6.php

In this exercise, you will both ways to connect to a database, and print the contents out of a table.

You will display this in a table (see demo). The database is test_alum The table I want you to look is call 'users' You are to list all the users and the following

attributeslast_namefirst_nameadminphonecellemail