Lecture6 display data by okello erick

Road Map
 MySQL Functions
 Connect to The Database
 Query the database
 Display table data
 Select individual records
2

MySQL Functions
mysql_connect
mysql_select_db
mysql_query
mysql_fetch_array
mysql_fetch_assoc
mysql_num_rows
mysql_close
Mysql_error
3

mysql_connect
You can connect to a MySQL database by using the mysql_connect
function.
A typical mysql_connect statement may look like the following:
$db = mysql_connect(“localhost”,
“root”, “password”);
4

mysql_select_db
The mysql_connect function returns a
database link identifier $db and its used
as an argument to the other MySQL
functions.
Selecting the database is a separate step
after you are connected to a MySQL
server; to do it, you use the
mysql_select_db function.
mysql_select_db(“mydb”, $db);
5

mysql_close
When you are finished using MySQL in a script, you close the
connection and free up its resources by using mysql_close, like this:
mysql_close($db);
6

mysql_query
The function to pass a SQL statement to MySQL is
mysql_query.
It takes two arguments the query itself and an
optional link identifier.
The following code executes a CREATE TABLE SQL
statement on the MySQL database for $db:
$sql = “CREATE TABLE mytable (col1
INT, col2 VARCHAR(10))”;
mysql_query($sql, $db);
7

mysql_fetch_array
PHP provides a convenient way to work with more than one item
from a selected row of data at a time.
By using mysql_fetch_array, you can create
An array from the query result that contains one element for each
column in the query.
8

mysql_fetch_array
$sql = “SELECT col1, col2 FROM
mytable”;
$res = mysql_query($sql, $conn);
while ($row = mysql_fetch_array($res))
{
echo “col1 =“.$row[“col1”];
echo “col2 =“.$row[“col2”].“ ”;
}
Each row of data is fetched in turn, and in each
pass of the loop, the entire row of data is available
in the array structure
9

mysql_fetch_assoc
mysql_fetch_assoc
Which also returns the row as an associative
array.
mysql_num_rows
The function mysql_num_rows returns the
number of rows found by the query, and you
can use this value to create a loop with
mysql_result to examine every row in the
result.
10

mysql_num_rows
$sql = “SELECT col1, col2 FROM mytable”;
$res = mysql_query($sql, $db);
for ($i=0; $i < mysql_num_rows($res); $i++) {
echo “col1 = “ . mysql_result($res, $i, 0);
echo “, col2 = “ . mysql_result($res, $i, 1) .
“ ”;
}
With the query used in this example,
because the column positions of col1 and
col2 are known, you can use mysql_result
with a numeric argument to specify each
one in turn.
11

Fetching Full Rows of Data
You can build a very powerful loop structure by
using mysql_fetch_array
$sql = “SELECT col1, col2 FROM mytable”;
$res = mysql_query($sql, $conn);
while ($row = mysql_fetch_array($res)) {
echo “col1 = “ . $row[“col1”];
echo “, col2 = “ . $row[“col2”] . “ ”;
}
Each row of data is fetched in turn, and in each pass of
the loop, the entire row of data is available in the array
structure
12

SQL Errors
When there is an error in a SQL statement,
it is not reported right away.
You should check the return value from
mysql_query to determine whether there
was a problem it is NULL if the query has
failed for any reason.
13

SQL Errors
The following example tries to perform an
invalid SQL statement (the table name is
missing from the DELETE command):
$sql = “DELETE FROM”;
$res = mysql_query($sql, $db);
if (!$res) {
echo “There was an SQL error”;
exit;
}
14

SQL Errors
If you want to find out why a call to
mysql_query failed, you must use the
mysql_error and mysql_errno functions to
retrieve the underlying MySQL warning text
and error code number.
if (!$res) {
echo “Error “ . mysql_errno() . “ in SQL “;
echo “<PRE>$sql</PRE>”;
echo mysql_error();
exit;
}
15

Connecting to Database
$username = "your_name";
$password = "your_password";
$hostname = "localhost";
//connection to the server
$dbhandle = mysql_connect($hostname,
$username, $password) or die("Unable to
connect to MySQL");
echo "Connected to MySQL";
16

Connecting to Database
//select a database to work with
$selected = mysql_select_db(“pet",
$dbhandle) or die("Could not select
examples");
//execute the SQL query and return records
$result = mysql_query("SELECT * FROM
cars");
17

Select data in a table
//fetch tha data from the table
while ($row = mysql_fetch_array($result)) {
echo "ID:".$row['id‘]." Name:".
$row['model‘]."Year: ". //display the results
$row['year‘]." ";
}
//close the connection
mysql_close($dbhandle);
18

Try out
<?php
$dbhost = 'localhost';
$dbuser = 'root';
$dbpass = '';
$conn = mysql_connect($dbhost, $dbuser, $dbpass);
if(! $conn ){die('Could not connect: ' . mysql_error());}
$sql = 'SELECT * FROM pet';
mysql_select_db(‘webdb');
$retval = mysql_query( $sql, $conn );
if(! $retval )
{
die('Could not get data: ' . mysql_error());
}
19

Try out
if(! $retval )
{
die('Could not get data: ' . mysql_error());
}
while($row = mysql_fetch_array($retval, MYSQL_ASSOC))
{
echo "Tutorial ID :{$row['tutorial_id']} ".
"Title: {$row['tutorial_title']} ".
"Author: {$row['tutorial_author']} ".
"Submission Date : {$row['submission_date']} ".
"-------------------------------- ";
}
echo "Fetched data successfullyn";
mysql_close($conn);
?>
20

Lecture6 display data by okello erick

More Related Content

What's hot (18)

Similar to Lecture6 display data by okello erick (20)

More from okelloerick (11)

Recently uploaded (20)

Lecture6 display data by okello erick