jQuery

 jQuery Syntax

The jQUery syntax is tailor made for selecting HTML elements and perform some action on the elements.
Basic syntax is : $(selector).action()

-> A $ sign to define/access jQuery
-> A (selector) to query HTML elements
-> A jQuery action() to be performed on the elements


Examples:
$(this).hide() - hides the current element.
$("p").hide() - hides all elements.
$(".test").hide() - hides all elements with class="test".
$("#test").hide() - hides the elements with id="test"

jQuery example

jQuery is a JavaScript Library. It is greatly simples JavaScript Programming. It is easy to learn.


Try it yourself......


Type this code Then click on a button to view the result
$(document).ready(function(){
  $("p").click(function(){
    $(this).hide();
  });
});

MySQL Tutorials

Create a Connection to a MySQL Database

Before you can access data in a database, you must create a connection to database.

In PHP, this is done with the mysql_connect()

Syntax

Mysql_connect(servername, username, password);

For Example:

$con=mysql_connect(“localhost”,”peter”,”abc123”);

If(!$con){

Die(‘Could not connect:’.mysql_error());

}

?>

Create a Database:
The CREATE DATABASE statement is used to create a database in MySQL.

Syntax:
CREATE DATABASE database_name

Create a Table:

The Create TABLE statment is used to create a table in MySQL.

Syntax:
CREATE TABLE table_name(

column_name1 data_type,
column_name2 data_type,
column_name3 data_type,


)
 

Regular Expression in php

The most wanted Regular Expression. Regular expression examples for decimals input.

PHP Array Function

The array functions allow you to manipulate arrays. PHP supports both simple and multi-dimensional arrays. there are also specific functions for populating arrays from database queries.  

The arrays functions are as follows->

sort(), asort(), ksort(), array(), array_chunk(), array_diff(), array_fill(), array_pop(), array_push(), array_search(), array_slice(), array_flip(),array_combine(), array_reserve(),array_walk(),ksort(),uksort(),reset(), rsort(),next(), pos() etc.

Mysql Interview Questions and Answers

1. Explain the difference MyISAM Static  and MyISAM Dynamic.

Ans- in MyISAM static all the fields have fixed width. The Dynamic MyISAM would include fields such as TEXT, BLOB, etc. to accommodate the data types with various lengths. MyISAM Static would be easier to restore in case of corruption, since even though you might lose some data, you know exactly where to look for the beginning of the next record.

2. What does myisamchk do?

It compressed the MyISAM tables , which reduces their disk usage.

3. Explain advantages of  InnoDB over  MyISAM?

Row level  locking, transactions, foreign key constraints and crash recovery.

4. Explain advantages of  MyISAM  over   InnoDB?

Much more conservative approach to disk space management each MyISAM table is stored in  a separate file, which could be compressed then with myisamchk if needed. With InnoDB the tables are stored in tablespace, and much further optimization is possible. All data except for TEXT and BLOB can occupy 8,000 bytes at most. No full text indexing is available for InnoDB.TRhe COUNT(*)s execute slower than in MyISAM due to tablespace complexity.

5. What are HEAP tables in MySQL?

HEAP tables are in memory. They are usually used for high-speed temporary storage. No TEXT or BLOB fields are allowed within HEAP tables. You can only use the comparison operators = and <=>. HEAP tables do not support AUTO_INCREAMENT. Indexes must be NOT NULL.

6. How do you control the max size of a HEAP table?

MySQL config variable max_heap_table_size

7. What are CSV tables?

Those are the special tables, data for which is saves into comm.-separate values file. They cannot be indexed.

Mysql Interview questions

1.  How do you start and stop Mysql on Windows?

    Ans- Net start Mysql, net stop Mysql

2.   How do you start Mysql on Linux?

Ans- /etc/init.d/mysql start

3.  Explain the difference between mysql and mysqli interfaces in PHP?

Ans- Mysqli is the object oriented version of mysql library functions.

4.  What’s the default port MySql Server?

Ans- 3306

5.   What does tee command do in Mysql?

Ans- tee followed by a filename turns on MySQL logging to a specified file. It can be stopped by command note.

6.   Can you save your connection settings to a conf file?

Ans- Yes, and name it~/.my.conf. You might want to change the permissions on the file to 600, so that it’s not readable by others.

7.  How do you change a password for an existing user via mysqladmin?

Ans- mysqladmin

-u root –p password “newpassword”

8. Use mysqldump to create a copy of the database?

     Ans- mysqldump –h mysqlhost –u

9.   Have you ever used Mysql Administrator and Mysql Query Brower? Describe the tasks you accomplished with these tools.

10. What are some good ideas regarding user security in MySQL?

Ans- There is no user without a password. There is no user without a user name. There is no user whose Host column contains % .

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