Load multiple javascript files asynchronously

In Every website, We have to include the JavaScript. We need to include multiple JavaScript file in single web page.

It's always prefer to include the javascript at the bottom of the page so that loading of content remain fast. So we should add at the bottom of the page.

We should also load the JavaScript files asynchronously, means load JavaScript file parallel.


There are two ways to load JavaScript file. Newer browsers have async attribute which load JavaScript asynchronously.
<scritp async="true" src="yourscript.js" type="text/javascript"></scritp>

Use custom JavaScript function to load javascript-file asynchronously.

<script type="text/javascript">
function loadScript (scriptpath){
    var s=document.getElementsByTagName('script')[0];
    var ss=document.createElement('script');
    ss.type='text/javascript';
    ss.async=true;
    ss.src= scriptpath;
    s.parentNode.insertBefore(ss,s);
}
</script>

Just call the loadScript function to load javascript file asynchronously. For Example.

<script type="text/javascript">
loadScript('/js/jQueryJSFIle1.js');
loadScript('/js/jQueryJSFIle2.js');
loadScript('/js/jQueryJSFIle3.js');
</script> 

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PHP Mysql Interview Questions and Answers for fresher and experienced

Question: How many ways we can retrieve the data in the result set of MySQL using PHP?
Following are different ways

$sqlQuery = mysql_query("SELECT id, name FROM users");
while ($row = mysql_fetch_array($result, MYSQL_BOTH)) {
    //$row have results
}

$sqlQuery = mysql_query("SELECT id, name FROM users");
while ($row = mysql_fetch_assoc($sqlQuery)) {
    //$row have results
}

$sqlQuery = mysql_query("SELECT id, name FROM users");
while ($row = mysql_fetch_object($sqlQuery)) {
   //$row have results
}

Question: How can we create a database using PHP and MySQL?

mysql_create_db('db_name');

Question: How can we repair a MySQL table?
Use any of below as per requirement:

REPAIR tablename; 
REPAIR tablename quick;
REPAIR tablename extended;

Question: How can we find the number of rows in a result set using PHP?

$sqlQuery = mysql_query("SELECT id, name FROM users");
$num = mysql_num_rows($sqlQuery);

Question: How to update auto increment value for 100000?

ALTER TABLE table_name AUTO_INCREMENT = 100000;

Question: How to get the current version number of MYSQL?

SELECT VERSION();

Question: What is difference between between NOW() and CURRENT_DATE()?
Now gives the current date, hour and minutes

select NOW()
//2015-06-03 19:17:23  

CURRENT_DATE gives the current date only.

select CURRENT_DATE()
//2015-06-03

Question: List all databases?

SHOW DATABASES

Question: What is mysql query to show the first 100 records?

SELECT * FROM user LIMIT 0,100

Question: How many TRIGGERS allows per table in mysql?
Following are 6 triggers in mysql for table.
1. BEFORE INSERT,
2. AFTER INSERT,
3. BEFORE UPDATE,
4. AFTER UPDATE,
5. BEFORE DELETE
6. AFTER DELETE



Question: What is difference between COMMIT and ROLLBACK?
COMMIT: Mostly it is used in transaction and commit means all process are completed successfully. Once commit done you can not revert.
ROLLBACK: Mostly it is used in transaction and ROLLBACK means all process are NOT completed successfully. So revert the db changes automatically.


Question: What is SAVEPOINT?
The SAVEPOINT statement is used to set a savepoint with a name in transaction. used for roll back the transaction to the named savepoint specified instead of all the changes.


Question: How to find the number of days between two dates?

$now = time(); // or your date as well
$newDate = strtotime("2010-01-01");
$datediff = $now - $$newDate;
echo floor($datediff/(60*60*24));

Question: How to find the number of hours between two dates?

$now = time(); // or your date as well
$newDate = strtotime("2010-01-01");
$datediff = $now - $$newDate;
echo floor($datediff/(60*60));

Question: How to find the number of minutes between two dates?

$now = time(); // or your date as well
$newDate = strtotime("2010-01-01");
$datediff = $now - $$newDate;
echo floor($datediff/(60));

Question: How do I get random item from an array?

$array = array('','s','d');
echo $array[array_rand($array)];

Question: How to update the max_allowed_packet mysql variable?
You can check the value of max_allowed_packet with following query.

SHOW VARIABLES LIKE 'max_allowed_packet'; 

For Update, You have to change in configuration mysql.
File Location in My Wamp Server: D:\wamp\bin\mysql\mysql5.6.17\my.ini
Now search with max_allowed_packet and update, as per requirement.


Question: List all the tables whose engine is InnoDB?

SELECT table_name FROM INFORMATION_SCHEMA.TABLES  WHERE ENGINE = 'InnoDB'

Question: How to update the column where NULL value set?

update `users` set phone='000000000' where  phone is NULL

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