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webdevelopmentcompanyindia · 4 years ago

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Five Common PHP Problems and Solutions

PHP is a vast subject that needs lots of study to get done. It is a most-used open fount general-purpose scripting language that is particularly satisfied for web development and can be inserted into HTML. Today we are giving answers of top Php related question which will help you to done the process. Here solutions are provided by the top PHP Development Company, AResourcePool.

How to store image in core Php using input type file?

Are you looking for the ways to upload or store an image in core Php using input type file? If yes, so here we are.

Php script is very popular as it is using with a HTML form to let the users to upload files to the different server. At first the files are uploaded into a transitory directory as well as, it moved to a target by a PHP script.

Here are some procedures of uploading a file. So, here you go:

· Open a page which contains a HTML where you can feature an image, text files, and browser button as well as submit button.

· Now, click on the browser button and select the desired file to upload from your computer or laptop.

· You will now see the entire file of the selected path. So, choose where you wanna store it and press submit button.

· The file will send to the directory which is only temporary on the server.

· Php script was particular as the outline handler in the form’s action attribute. Now check is the file exist and then copy to the directory.

· You can make sure your success by using PHP script.

Meanwhile, it is really important to seek permission when writing files for permanent location or for temporary location. Whatever file you are uploading can be the image file or it can be the text file or whatever document you are uploading.

How to create an upload form?

To create an upload form you will need HTM coding because it has certain attribute of post as well as enctype attribute which is set to multipart.

<?php

if(isset($_FILES[‘image’])){

$errors= array();

$file_name = $_FILES['image’]['name’];

$file_size =$_FILES['image’]['size’];

$file_tmp =$_FILES['image’]['tmp_name’];

$file_type=$_FILES['image’]['type’];

$file_ext=strtolower(end(explode(’.’,$_FILES['image’]['name’])));

$extensions= array(“jpeg”,“jpg”,“png”);

if(in_array($file_ext,$extensions)=== false){

$errors[]=“extension not allowed, please choose a JPEG or PNG file.”;

}

if($file_size > 2097152){

$errors[]='File size must be excately 2 MB’;

}

if(empty($errors)==true){

move_uploaded_file($file_tmp,“images/”.$file_name);

echo “Success”;

}else{

print_r($errors);

}

<html>

<body>

</form>

</body>

</html>

How can I test to see if value is 0 or null in PHP?

Php is a vast subject that contains many elements and one of the major elements of Php is to check 0, null or empty and isset status. It has various functions to check whether it is good or not or to test the value of the variables. There are three important functions of Php such as isset(), empty() and is_null(). This factors help to return a Boolean value. Boolean value is the used to determine the value of these functions. The result would be unexpected if it is not used in a right ways. There are two functions which functions opposite isset() and empty(). Well, it is not always true there is certain difference between all. So, here have a look at these functions:

1. isset()From PHP manual – isset():

Isset is used to decide that if a variable is set and is not NULL. If we say in other words then, it is used to determine the return is true only when not null is the variable.

2. empty()From PHP Manual – empty():

Empty is used to decide that if a variable is empty.If we talk in other terms then, it will return true if the variable is empty. It will show false, array(), NULL, “0?, 0, and an unset variable.

3. is_null()From PHP Manual – is_null():

Null is used to find if a variable is Null or not. In other words if we say then the returns true then, only when the variable shows null result. is_null() is opposite of isset(), except for one difference that isset() can be applied to unknown variables, but is_null() only to declared variables.

How to delete row from table using PHP pdo?

You can utilize the assignments table in the example database for the showing. Before going ahead with this instructional exercise, you ought to pursue the PHP MySQL make table instructional exercise to make the errands table and addition test information for rehearsing.

PHP MySQL Delete: Tasks Table:To erase information in a table, you utilize the accompanying advances: Associate with the MySQL database by making another case of the PDO object.

First of all, build a DELETE explanation to erase a column, numerous lines, or all lines in a table. On the off chance that you need to erase all columns in a major table rapidly and all the more proficiently, you utilize the TRUNCATE TABLE proclamation. Execute the DELETE articulation by calling the executive() strategy for the PDO object or the execute() technique for the PDOStatement object.

· PHP MySQL Delete information models

· PHP MySQL: erase a solitary column model

· To erase a solitary column in a table, you utilize the DELETE articulation with a WHERE condition that determines which line to erase.

· The accompanying content erases a column with id 2 in the assignments table.

How it functions?

When we talk about__construct() technique for the DeleteDataDemo class, we interface with the MySQL database by starting a case of the PDO class, and in the __destruct() strategy, we close the database association. The erase() technique acknowledges the id as the contention. In the first place, we call the get ready() technique for the PDO item to set up the DELETE explanation for execution, and after that we pass an exhibit that contains values comparing to the named placeholders in the DELETE proclamation to the execute() strategy for the PDOStatement object.

To erase the undertaking with id 2, we make an example of the DeleteDataDemo class and call the erase() strategy.

PHP MySQL: erase all columns in a table precedents

There are two different ways to erase all columns in a table:

· Issue a DELETE explanation without a WHERE statement.

· Issue a TRUNCATE TABLE explanation.

Getting Data from Multiple Databases:

There can be different issues which can face while fetching data from multiple databases but, issue you will have is consolidating the information. In a solitary database you keep up information honesty by characterizing outside keys. Different tables may have things identified with clients, so they may have a user_id field.

In a solitary database you would characterize a remote key connection between that user_id field and the id field on the client table, which means just existing id esteems from the client table, could be embedded in the othertable::user_id field. You can’t do outside key connections between tables in various databases, so I don’t have the foggiest idea how you’re going to interface the two arrangements of information into a solitary dataset.

Notwithstanding, expect you have a pseudo remote key, as above, however itwon’t be utilized by the databases to look after honesty. At that point need to do some sort of for/for each circle more than one dataset, remove the key which joins it to the next dataset, at that point glance through the second dataset for the coordinating key.

So, there are certain steps which involved in it so, have a look:

· make first association config ($conn1 = mysqli_connect($server1, $username, $password, $dbname)

· make second association config ($conn2 = mysqli_connect($server2, $username, $password, $dbname2);)

· select information with $conn config and store into $result variable (exhibit)

· for each $result, embed it into second database utilizing $conn2

How to display data record in database from vertical to horizontal:

There are many different ways to arrange data in a vertical to the horizontal database in Php. You will get two favourable circumstances and weaknesses to these strategies for social database information association. I completely depend on the requirements of the business as well it also depends on the need for the development.

The traditional way of any data in a table is a horizontal layout. Whatever data is recorded is go in a row and columns format runs horizontally. On the other hand, the second way is vertical. This way is very specific as well as it stores data that only have a column for real data. Here have a look at the example of data record in database from vertical to horizontal.

Table for Horizontal:

First_Name

Last_Name

Dept

Sex

123

Vlad

Kofman

234

Jim

Cramer

Marketing

456

Olimpia

Dukakis

Accounting

Table for Vertical

Key

Value

123

First_Name

Vlad

234

First_Name

Jim

456

First_Name

Olimpia

123

Last_Name

Kofman

234

Last_Name

Cramer

456

Last_Name

Dukakis

123

Dept

234

Dept

Marketing

456

Dept

Accounting

123

Sex

234

Sex

456

Sex

How enable in php long query strings:

Selecting Encrypted Username from DB:

There is very common question always hit the mind of the users that how Selecting Encrypted Username from DB? So, to encrypt the process does the data in the database unreadable from data in word processors. There can be no one decipher of its data when the database is encrypted.

Any database can be encrypted by utilizing the standard access menus. In both, the cases database that you are encrypting cannot be opened.

Follow this step to Encrypted Username from DB:

· Step 1: Select the tool by going to the setting. You will get options like Encrypt/Decrypt Database in the menu options.

· Step 2: You will see the encrypt/decrypt database dialogue from which choose the file which you want to encrypt. Press Okay.

· Step 3: If a user chooses the name which already exists in the files then, access will remove the original file after it concludes the process of encryption is successful. One of the best things that you can do in this situation is to take back up of the original database.

Encrypting with Code:

If you have used runtime version of Access to distribute your application and wants to give all the Php users the capability to encrypt the database you have to enter database course such as ADO. The following code will look like this:

Sub Encrypt(strDBNotEncrypted As String, _

strDBEncrypted As String)

Dim je As Nwe JRO.JetEngine

Je.CompactDatabase SourceConnection:=“Data Source=” _

& strDBNotEncrypted & “;”, _

DestConnection:=“Data Source=” & strDBEncrypted & _

"; Jet OLEDB:Encrypt Database=True"

End Sub

That’s all the folk about Php. If you are looking for such services you can contact Aresourcepool. The company has the best solution for all the above mentioned concept.

#php development company #php development #php development company india

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datacouncil11-blog · 8 years ago

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PHP interview questions and Openings for freshers

PHP interview questions and answers for freshers

Welcome !!!. In this section we are providing you some frequently asked PHP Interview Questions which will help you to win interview session easily. Candidates must read this section,Then by heart the questions and answers. Also, review sample answers and advice on how to answer these typical interview questions. PHP is an important part of the web world, and every web developer should have the basic knowledge in PHP.Common PHP interview questions, which should help you become a best PHP codder. We hope you find these questions useful. If you are an interviewer, Take the time to read the common interview questions you will most likely be asked.

For more information about placement and interviews visit us at - https://www.datacouncil.in/

or Walk in to our institute at karvenagar, Pune.

What is PHP?PHP is a server side scripting language commonly used for web applications. PHP has many frameworks and cms for creating websites.Even a non technical person can cretae sites using its CMS.WordPress,osCommerce are the famus CMS of php.It is also an object oriented programming language like java,C-sharp etc.It is very eazy for learning

What is the use of "echo" in php?It is used to print a data in the webpage, Example: , The following code print the text in the webpage

How to include a file to a php page?We can include a file using "include() " or "require()" function with file path as its parameter.

What's the difference between include and require?If the file is not found by require(), it will cause a fatal error and halt the execution of the script. If the file is not found by include(), a warning will be issued, but execution will continue.

require_once(), require(), include().What is difference between them?require() includes and evaluates a specific file, while require_once() does that only if it has not been included before (on the same page). So, require_once() is recommended to use when you want to include a file where you have a lot of functions for example. This way you make sure you don't include the file more times and you will not get the "function re-declared" error.

Differences between GET and POST methods ?We can send 1024 bytes using GET method but POST method can transfer large amount of data and POST is the secure method than GET method .

How to declare an array in php?Eg : var $arr = array('apple', 'grape', 'lemon');

What is the use of 'print' in php?This is not actually a real function, It is a language construct. So you can use with out parentheses with its argument list. Example print('PHP Interview questions'); print 'Job Interview ');

What is use of in_array() function in php ?in_array used to checks if a value exists in an array

What is use of count() function in php ?count() is used to count all elements in an array, or something in an object

What's the difference between include and require?It's how they handle failures. If the file is not found by require(), it will cause a fatal error and halt the execution of the script. If the file is not found by include(), a warning will be issued, but execution will continue.

What is the difference between Session and Cookie?The main difference between sessions and cookies is that sessions are stored on the server, and cookies are stored on the user's computers in the text file format. Cookies can't hold multiple variable while session can hold multiple variables..We can set expiry for a cookie,The session only remains active as long as the browser is open.Users do not have access to the data you stored in Session,Since it is stored in the server.Session is mainly used for login/logout purpose while cookies using for user activity tracking

How to set cookies in PHP?Setcookie("sample", "ram", time()+3600);

How to Retrieve a Cookie Value?eg : echo $_COOKIE["user"];

How to create a session? How to set a value in session ? How to Remove data from a session?Create session : session_start(); Set value into session : $_SESSION['USER_ID']=1; Remove data from a session : unset($_SESSION['USER_ID'];

what types of loops exist in php?for,while,do while and foreach (NB: You should learn its usage)

MYSQL

How to create a mysql connection?mysql_connect(servername,username,password);

How to select a database?mysql_select_db($db_name);

How to execute an sql query? How to fetch its result ?$my_qry = mysql_query("SELECT * FROM `users` WHERE `u_id`='1'; "); $result = mysql_fetch_array($my_qry); echo $result['First_name'];

Write a program using while loop$my_qry = mysql_query("SELECT * FROM `users` WHERE `u_id`='1'; "); while($result = mysql_fetch_array($my_qry)) { echo $result['First_name'.]." "; }

How we can retrieve the data in the result set of MySQL using PHP?

What is the use of explode() function ?Syntax : array explode ( string $delimiter , string $string [, int $limit ] ); This function breaks a string into an array. Each of the array elements is a substring of string formed by splitting it on boundaries formed by the string delimiter.

What is the difference between explode() and split() functions?Split function splits string into array by regular expression. Explode splits a string into array by string.

What is the use of mysql_real_escape_string() function?It is used to escapes special characters in a string for use in an SQL statement

Write down the code for save an uploaded file in php.if ($_FILES["file"]["error"] == 0) { move_uploaded_file($_FILES["file"]["tmp_name"], "upload/" . $_FILES["file"]["name"]); echo "Stored in: " . "upload/" . $_FILES["file"]["name"]; }

How to create a text file in php?$filename = "/home/user/guest/newfile.txt"; $file = fopen( $filename, "w" ); if( $file == false ) { echo ( "Error in opening new file" ); exit(); } fwrite( $file, "This is a simple test\n" ); fclose( $file );

How to strip whitespace (or other characters) from the beginning and end of a string ?The trim() function removes whitespaces or other predefined characters from both sides of a string.

What is the use of header() function in php ?The header() function sends a raw HTTP header to a client browser.Remember that this function must be called before sending the actual out put.For example, You do not print any HTML element before using this function.

How to redirect a page in php?The following code can be used for it, header("Location:index.php");

How stop the execution of a php scrip ?exit() function is used to stop the execution of a page

How to set a page as a home page in a php based site ?index.php is the default name of the home page in php based sites

How to find the length of a string?strlen() function used to find the length of a string

what is the use of rand() in php?It is used to generate random numbers.If called without the arguments it returns a pseudo-random integer between 0 and getrandmax(). If you want a random number between 6 and 12 (inclusive), for example, use rand(6, 12).This function does not generate cryptographically safe values, and should not be used for cryptographic uses. If you want a cryptographically secure value, consider using openssl_random_pseudo_bytes() instead.

what is the use of isset() in php?This function is used to determine if a variable is set and is not NULL

What is the difference between mysql_fetch_array() and mysql_fetch_assoc() ?mysql_fetch_assoc function Fetch a result row as an associative array, While mysql_fetch_array()fetches an associative array, a numeric array, or both

What is mean by an associative array?Associative arrays are arrays that use string keys is called associative arrays.

What is the importance of "method" attribute in a html form?"method" attribute determines how to send the form-data into the server.There are two methods, get and post. The default method is get.This sends the form information by appending it on the URL.Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send.

What is the importance of "action" attribute in a html form?The action attribute determines where to send the form-data in the form submission.

What is the use of "enctype" attribute in a html form?The enctype attribute determines how the form-data should be encoded when submitting it to the server. We need to set enctype as "multipart/form-data" when we are using a form for uploading files

How to create an array of a group of items inside an HTML form ?We can create input fields with same name for "name" attribute with squire bracket at the end of the name of the name attribute, It passes data as an array to PHP. For instance :

Define Object-Oriented MethodologyObject orientation is a software/Web development methodology that is based on the modeling a real world system.An object is the core concept involved in the object orientation. An object is the copy of the real world enity.An object oriented model is a collection of objects and its inter-relationships

How do you define a constant?Using define() directive, like define ("MYCONSTANT",150)

How send email using php?To send email using PHP, you use the mail() function.This mail() function accepts 5 parameters as follows (the last 2 are optional). You need webserver, you can't send email from localhost. eg : mail($to,$subject,$message,$headers);

How to find current date and time?The date() function provides you with a means of retrieving the current date and time, applying the format integer parameters indicated in your script to the timestamp provided or the current local time if no timestamp is given. In simplified terms, passing a time parameter is optional - if you don't, the current timestamp will be used.

Difference between mysql_connect and mysql_pconnect?There is a good page in the php manual on the subject, in short mysql_pconnect() makes a persistent connection to the database which means a SQL link that do not close when the execution of your script ends. mysql_connect()provides only for the databasenewconnection while using mysql_pconnect , the function would first try to find a (persistent) link that's already open with the same host, username and password. If one is found, an identifier for it will be returned instead of opening a new connection... the connection to the SQL server will not be closed when the execution of the script ends. Instead, the link will remain open for future use.

What is the use of "ksort" in php?It is used for sort an array by key in reverse order.

What is the difference between $var and $$var?They are both variables. But $var is a variable with a fixed name. $$var is a variable who's name is stored in $var. For example, if $var contains "message", $$var is the same as $message.

What are the encryption techniques in PHPMD5 PHP implements the MD5 hash algorithm using the md5 function, eg : $encrypted_text = md5 ($msg);mcrypt_encrypt :- string mcrypt_encrypt ( string $cipher , string $key , string $data , string $mode [, string $iv ] ); Encrypts plaintext with given parameters

What is the use of the function htmlentities?htmlentities Convert all applicable characters to HTML entities This function is identical to htmlspecialchars() in all ways, except with htmlentities(), all characters which have HTML character entity equivalents are translated into these entities.

How to delete a file from the systemUnlink() deletes the given file from the file system.

How to get the value of current session id?session_id() function returns the session id for the current session.

What are the differences between mysql_fetch_array(), mysql_fetch_object(), mysql_fetch_row()?

What are the different types of errors in PHP ?Here are three basic types of runtime errors in PHP:

what is sql injection ?SQL injection is a malicious code injection technique.It exploiting SQL vulnerabilities in Web applications

What is x+ mode in fopen() used for?Read/Write. Creates a new file. Returns FALSE and an error if file already exists

How to find the position of the first occurrence of a substring in a stringstrpos() is used to find the position of the first occurrence of a substring in a string

What is PEAR?PEAR is a framework and distribution system for reusable PHP components.The project seeks to provide a structured library of code, maintain a system for distributing code and for managing code packages, and promote a standard coding style.PEAR is broken into three classes: PEAR Core Components, PEAR Packages, and PECL Packages. The Core Components include the base classes of PEAR and PEAR_Error, along with database, HTTP, logging, and e-mailing functions. The PEAR Packages include functionality providing for authentication, networking, and file system features, as well as tools for working with XML and HTML templates.

Distinguish between urlencode and urldecode?This method is best when encode a string to used in a query part of a url. it returns a string in which all non-alphanumeric characters except -_. have replece with a percentege(%) sign . the urldecode->Decodes url to encode string as any %and other symbole are decode by the use of the urldecode() function.

What are the different errors in PHP?In PHP, there are three types of runtime errors, they are:Warnings: These are important errors. Example: When we try to include () file which is not available. These errors are showed to the user by default but they will not result in ending the script. Notices: These errors are non-critical and trivial errors that come across while executing the script in PHP. Example: trying to gain access the variable which is not defined. These errors are not showed to the users by default even if the default behavior is changed. Fatal errors: These are critical errors. Example: instantiating an object of a class which does not exist or a non-existent function is called. These errors results in termination of the script immediately and default behavior of PHP is shown to them when they take place. Twelve different error types are used to represent these variations internally.

1. mysql_fetch_row

2. mysql_fetch_array

3. mysql_fetch_object

4. mysql_fetch_assoc

Mysql_fetch_array Fetch a result row as an associative array, a numeric array, or both.

mysql_fetch_object ( resource result ) Returns an object with properties that correspond to the fetched row and moves the internal data pointer ahead. Returns an object with properties that correspond to the fetched row, or FALSE if there are no more rows

mysql_fetch_row() fetches one row of data from the result associated with the specified result identifier. The row is returned as an array. Each result column is stored in an array offset, starting at offset 0.

1. Notices: These are trivial, non-critical errors that PHP encounters while executing a script - for example, accessing a variable that has not yet been defined. By default, such errors are not displayed to the user at all - although you can change this default behavior.

2. Warnings: These are more serious errors - for example, attempting to include() a file which does not exist. By default, these errors are displayed to the user, but they do not result in script termination.

3. Fatal errors: These are critical errors - for example, instantiating an object of a non-existent class, or calling a non-existent function. These errors cause the immediate termination of the script, and PHP's default behavior is to display them to the user when they take place.

For more information about placement and interviews visit us at - https://www.datacouncil.in/

or Walk in to our institute at karvenagar, Pune.

#php classes in pune #learn php #best php classes in pune #php interview questions

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