What is mysql_free_result()?

mysql_free_result() only needs to be called if you are concerned about how much memory is being used for queries that return large result sets. All associated result memory is automatically freed at the end of the script's execution.
Returns TRUE on success or FALSE on failure.

How to use mysql_fetch_object?

object mysql_fetch_object ( resource result)


Returns an object with properties that correspond to the fetched row, or FALSE if there are no more rows.
mysql_fetch_object() is similar to mysql_fetch_array(), with one difference - an object is returned, instead of an array. Indirectly, that means that you can only access the data by the field names, and not by their offsets (numbers are illegal property names).

Note: Field names returned by this function are case-sensitive.

<?php
/* this is valid */echo $row->field;/* this is invalid */echo $row->0;
?>

<?php
mysql_connect("hostname", "user", "password");mysql_select_db("mydb");$result = mysql_query("select * from mytable");
while ($row = mysql_fetch_object($result)) {
    echo $row->user_id;
    echo $row->fullname;
}mysql_free_result($result);?>

How to use mysql_fetch_assoc?

array mysql_fetch_assoc ( resource result)


Returns an associative array that corresponds to the fetched row, or FALSE if there are no more rows.
mysql_fetch_assoc() is equivalent to calling mysql_fetch_array() with MYSQL_ASSOC for the optional second parameter. It only returns an associative array. This is the way mysql_fetch_array() originally worked. If you need the numeric indices as well as the associative, use mysql_fetch_array().
If two or more columns of the result have the same field names, the last column will take precedence. To access the other column(s) of the same name, you either need to access the result with numeric indices by using mysql_fetch_row() or add alias names. See the example at the mysql_fetch_array() description about aliases.
An important thing to note is that using mysql_fetch_assoc() is not significantly slower than using mysql_fetch_row(), while it provides a significant added value.

An expanded mysql_fetch_assoc() example

<?php

$conn = mysql_connect("localhost", "mysql_user", "mysql_password");

if (!$conn) {
    echo "Unable to connect to DB: " . mysql_error();
    exit;
}
   
if (!mysql_select_db("mydbname")) {
    echo "Unable to select mydbname: " . mysql_error();
    exit;
}
$sql = "SELECT id as userid, fullname, userstatus
        FROM   sometable
        WHERE  userstatus = 1";
$result = mysql_query($sql);

if (!$result) {
    echo "Could not successfully run query ($sql) from DB: " . mysql_error();
    exit;
}

if (mysql_num_rows($result) == 0) {
    echo "No rows found, nothing to print so am exiting";
    exit;
}
while ($row = mysql_fetch_assoc($result)) {
    echo $row["userid"];
    echo $row["fullname"];
    echo $row["userstatus"];
}
mysql_free_result($result);
?>

How to use mysql_connect() example

<?php
$link = mysql_connect('localhost', 'mysql_user', 'mysql_password');
if (!$link) {
    die('Could not connect: ' . mysql_error());
}
echo 'Connected successfully';mysql_close($link);?>

How to use mysql_affected_rows?

mysql_affected_rows -- Get number of affected rows in previous MySQL operation

mysql_affected_rows() returns the number of rows affected by the last INSERT, UPDATE or DELETE query associated with link_identifier. If the link identifier isn't specified, the last link opened by mysql_connect() is assumed.

Example
<?php/* connect to database */$link = mysql_connect('localhost', 'mysql_user', 'mysql_password');
if (!$link) {
    die('Could not connect: ' . mysql_error());
}mysql_select_db('mydb');
/* this should return the correct numbers of deleted records */mysql_query('DELETE FROM mytable WHERE id < 10');printf("Records deleted: %d\n", mysql_affected_rows());
/* with a where clause that is never true, it should return 0 */mysql_query('DELETE FROM mytable WHERE 0');printf("Records deleted: %d\n", mysql_affected_rows());?>

Output:

Records deleted: 10
Records deleted: 0

Example2

<?php/* connect to database */mysql_connect("localhost", "mysql_user", "mysql_password") 
or
    die("Could not connect: " . mysql_error());mysql_select_db("mydb");
/* Update records 
*/mysql_query("UPDATE mytable SET used=1 WHERE id 
< 10");printf 
("Updated records: 
%d\n", mysql_affected_rows());mysql_query("COMMIT");?> 

Output

Updated Records: 10




What is the use of "ksort" in php?

it is used for sort an array by key in reverse order.

How to calculate the sum of values in an array ?

"array_sum" method used for calculate sum of values in an array