PHP and MySQL Interview Questions and Answers

PHP is the most widely used open-source programming language that is created specifically for developing dynamic websites and mobile APIs. PHP is the most demanded programming skill in various companies at present. Also, PHP developers have a great demand at present. Most of the companies are looking for Developers with PHP skills on their resume. If you are planning to begin a career in PHP, then, you can start your career now in PHP as it is the right time to begin.

To qualify oneself for the position of PHP Developer in an Interview, one should be well-prepared for the PHP Interview Questions And Answers that are asked to them in an Interview. Below are the PHP and MySQL Interview Questions and answers for freshers and Experienced. As MySQL is the database for PHP we have enlisted a few questions that are related to MySQL.

PHP and MySQL Introductory Interview Questions

1. What is PHP?

PHP is a widely used open-source programming language for developing dynamic websites and mobile APIs. It’s a popular choice among companies, and PHP developers are in high demand.

2. What is SQL? 

SQL (Structured Query Language) is a computer language used to communicate with and manage relational databases. It provides a standard way to define, manipulate, and retrieve data from databases.

3. Why is PHP a good career choice?

PHP is a versatile language with a large community and abundant resources. Starting a career in PHP now is a wise decision due to its current popularity and job market.

Basic PHP and MySQL Interview Questions

These are the PHP Basic Interview Questions to know mandatorily before attending any interviews.

4. Explain the echo function.

The echo function can output multiple strings and return 1.

5. What is the script engine in PHP?

The script engine in PHP is Zend Engine 2.

6. What does the trim() function do?

The trim() function removes predefined characters and whitespace from both sides of a string.

7. How can you retrieve data from MySQL result sets using PHP?

You can use four methods: mysql_fetch_row, mysql_fetch_assoc, mysql_fetch_array, and mysql_fetch_object.

8. What is the limitation of the print function?

The print function can only take one argument as a parameter.

9. What is the in_array() function?

The in_array() function searches an array for a specific value.

10. What are the uses of the count() function in PHP?

The count() function counts the number of elements in an array.

11. How can you include a file in a PHP page?

You can use the require() or include() function with the file path as a parameter.

12. What are the types of SQL? 

Types of SQL:

DDL (Data Definition Language)

Used to define the database structure, including creating, modifying, and deleting tables, indexes, and views.

DML (Data Manipulation Language)

Used to insert, update, delete, and retrieve data from tables.

DCL (Data Control Language)

Used to control access to data, including granting and revoking privileges.

TCL (Transaction Control Language)

Used to manage transactions, including commit and rollback.

This is an important topic which is asked in PHP interview questions for freshers.

13. What are the 5 basic SQL commands?

5 Basic SQL Commands are

• SELECT: Retrieves data from a database table.

• INSERT: Inserts new data into a database table.

• UPDATE: Modifies existing data in a database table.

• DELETE: Removes data from a database table.

• CREATE: Creates new database objects, such as tables, views, and indexes.

14. What are 4 SQL languages?

• SQL-92: The standard SQL language defined in 1992.

• SQL-99: A revised standard released in 1999.

• SQL:2003: Another revision of the standard released in 2003.

• SQL:2011: The latest revision of the standard released in 2011.

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15. What is rollback in SQL?

Rollback is a transaction control language (TCL) command used to undo changes made to a database since the last commit point. If a transaction encounters an error or is explicitly rolled back, all changes made within that transaction are reversed, restoring the database to its previous state.

16. What is DDL in SQL?

DDL (Data Definition Language) is used to define the structure of a database. It includes commands to create, modify, and delete database objects such as:

• Tables: Used to store data.

• Indexes: Used to improve query performance.

• Views: Used to provide a virtual view of data from multiple tables.

• Constraints: Used to enforce data integrity rules.

Examples of DDL commands:

• CREATE TABLE: Creates a new table.
• ALTER TABLE: Modifies an existing table.
• DROP TABLE: Deletes a table.
• CREATE INDEX: Creates an index on a table.
• DROP INDEX: Deletes an index.

17. How do you create a database using MySQL and PHP?

You can create a MySQL database using mysql_create_db(“Database Name”).

18. List three features of MySQL.

• MySQL is easy and reliable to use.
• MySQL supports various programming languages like PHP, Java, Perl, and C++.
• MySQL supports standard SQL (Structured Query Language).

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19. What language is MySQL written in?

MySQL is written in C and C++. The SQL parser is written in Yacc.

20. Mention the technical specifications of MySQL.

Drivers, JSON support, graphical tools, flexible structure, high performance, geo-spatial support, OLTP and transactions, MySQL Enterprise Monitor, MySQL Enterprise Security, manageability and ease of use, replication and high availability, security and storage management.

21. What are the data types in PHP?

• Compound types: Array, Object, Callable
• Scalar types: Float, String, Integer, Boolean
• Special types: Null, Resource

22. Mention the frameworks in PHP.

Yii 2, Symfony, CakePHP, CodeIgniter, Zend Framework

One of the Core Php Interview Questions that is regularly asked is this one.

23. What is unset()?

The unset() function sets a variable to “undefined”.

24. What are the three main error types?

Fatal, E-Notices, E-Warnings

25. How do you get a client’s IP address?

$_SERVER[“REMOTE_ADDR”];

26. What is the explode function?

The explode function converts a string into an array using a delimiter.

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27. How do you stop the execution of a PHP script?

By using the exit(); function.

28. Define the implode function.

The implode function is the opposite of the explode function. It implodes an array into a string.

This is one of the PHP Interview Questions For Experienced to know before attending an interview.

PHP and MySQL Advanced Topics

29. What are the constants in PHP?

-FILE-, -LINE-, -CLASS-, -METHOD-, -FUNCTION-

30. Mention the table names that are present in MySQL.

ISAM, Heap, Merge, MyISAM, InnoDB

31. What are the uses of PHP?

PHP can gather data from files, save data to a file, and send data through email. It can also delete, add, and modify elements within a database, and access cookie variables.

32. List the pro features of PHP and MySQL.

Data security, on-demand scalability, high performance, round-the-clock availability, complete workflow control, flexibility of open source, comprehensive transactional support.

33. Define PHP 5.

PHP 5 is a server-side scripting language used for creating dynamic and interactive web pages. It’s a free and useful alternative to Microsoft’s ASP.

34. Define static websites.

Static websites have content that cannot be changed once the scripts are run.

35. What are dynamic websites?

Dynamic websites have scripts that can be changed at runtime, and their content is regenerated constantly after user visits or reloads.

36. What are the magic functions available in PHP?

_destruct(), _call(), _get(), _set(), _isset(), _unset(), _construct(), _sleep(), _clone(), _invoke(), _toString(), _wakeup(), _setState(), _debugInfo()

37. How do you stop executing a PHP script?

exit(); function.

One of the significant and typical PHP interview questions and answers is this one.

38. What is the isset() function?

It checks if a variable is set and not null.

39. What is the way to destroy a variable or object?

unset() function.

40. What is the MIME type required for sending attachment mail?

multipart/mixed.

41. What is trigger in SQL?

A trigger is a stored procedure that executes automatically when a specific event occurs on a table. These events can be:

• INSERT: When a new row is inserted into the table.
• UPDATE: When an existing row is updated in the table.
• DELETE: When a row is deleted from the table.

Triggers are used to enforce data integrity, automate tasks, and implement complex business rules.

With the aid of these PHP interview questions for freshers, so that you may increase your knowledge and succeed in your interview.

42. What is a save point in SQL?

A save point is a marker within a transaction that allows you to roll back the transaction to that point if necessary.

This is useful for performing complex operations within a transaction and providing a way to recover from errors or unexpected situations without having to roll back the entire transaction.

43. What is VARCHAR in SQL?

VARCHAR is a variable-length character data type in SQL. It is used to store character strings of varying lengths. Unlike the CHAR data type, which has a fixed length, VARCHAR allocates only the necessary space to store the string, making it more efficient for storing strings of varying sizes.

The syntax for declaring a VARCHAR column is:

SQL

VARCHAR(maximum_length)

For example, to create a column named name that can store up to 50 characters, you would use:

SQL

CREATE TABLE customers (

id INT PRIMARY KEY,

name VARCHAR(50)

);

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44. What are the various types of triggers possible in MySQL?

• Before Insert, After Insert, Before Delete, After Delete, Before Update, After Update

It is regarded as one of the PHP Basic Interview Questionsthat candidates must be familiar with before attending an interview.

45. What is the session time of PHP?

The default session time in PHP is 24 minutes (1440 seconds).

46. Mention the uses of PHP and MySQL.

• PHP is a scripting language used in web development.
• MySQL is a relational database management system.

47. What are TEXT and BLOB in MySQL?

• TEXT is a case-sensitive BLOB and stores text values.
• BLOB stands for “large binary object” and is used for holding variable amounts of data.

48. What are the types of BLOB?

The types of BLOB in MySQL are:

• BLOB

The basic BLOB type, can store up to 65,535 bytes of data.

• TINYBLOB

A smaller version of BLOB, which can store up to 255 bytes of data.

• MEDIUMBLOB

A medium-sized BLOB, can store up to 16,777,215 bytes of data.

• LONGBLOB

The largest BLOB type, which can store up to 4,294,967,295 bytes of data.

One of the Core Php Interview Questions that is regularly asked is this one.

49. What are the types of TEXT in MySQL?

TEXT, TINYTEXT, MEDIUMTEXT, LONGTEXT

50. Name the variable’s scope in PHP.

Local Scope, Global Scope, Static Scope

51. How would you redirect a page in PHP?

header(“Location:HomePage.php”);

52. List any three disadvantages of MySQL.

Not suitable for large-scale databases, cannot support STORED PROCEDURES and COMMIT function before version 5.0, functionality primarily dependent on add-ons.

53. How to destroy a cookie?

By setting cookies in the past.

54. What are the possible ways to pass variables via navigation between pages?

GET/QueryString, POST

55. What is the one main distinction between PHP 4 and PHP 5?

PHP 5 offers more object-oriented programming (OOP) features compared to PHP 4.

56. What is the function used in removing escape characters from a string?

stripslashes function.

You can better prepare for the interview by preparing for these PHP Basic Interview Questions.

57. What are the functions used in sorting an array?

sort(), asort(), arsort(), ksort(), rsort(), usort(), natsort(), natcasesort(), uksort(), array_multisort()

58. Which method is used in sending the Simple Mail Transfer Protocol using PHP?

mail($EmailAddress, “Subject”, $MessageBody);

59. From the given statements, which one is correct?

When $x = null;, empty($x) returns TRUE, isset($x) returns FALSE, and is_null($x) returns FALSE.

60. What is the immediate way to escape incoming data?

Enable the magic quote entry in the PHP configuration file.

61. Mention the method used in tweaking an object’s cloning behaviour.

__clone(). It is one of the crucial PHP Interview Questions for Freshersfrequently brought up throughout the interview.

62. How can you get the current date in MySQL?

SELECT CURRENT_DATE();

63. What is the default port number of MySQL?

The default port number for MySQL is 3306.

This port number is a standard convention used by MySQL servers to listen for incoming connections. When you install MySQL on a system, it typically configures itself to use this port. However, you can also customise it to use a different port if necessary.

MySQL installation is one of the key topics explored in Php Interview Questions And Answers, to test freshers

64. Name the tools through which you can draw E-R diagrams for MySQL.

Case Studio, Smart Draw

65. List a few functions of IMAP.

imap_body, imap_check, imap_delete, imap_mail

66. What are the current versions of MySQL and PHP?

MySQL – 5.0, PHP – 5.1 Beta

67. What are the types of arrays in PHP?

Indexed Array, Associative Array, Multi-Dimensional Array

68. What are the built-in functions that add value to the end of an array?

into_array(), inend_array(), array_push(), array_unshift()

69. What are the features of PHP7?

Spaceship operator, Generator delegation, Anonymous classes, Closure:: call method, Group use declaration, Scalar type declarations, Return type declarations, Null coalescing operator (??), Constant arrays using define(), Generator return expressions.

It is one of the important PHP Interview Questions For Experienced that come up repeatedly during the interview.

70. List the Content Management Systems in PHP.

WordPress, Joomla, Magento, Drupal

71. How many columns can we create for the index?

For a Standard Table, we can create 16 indexed columns.

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Advanced PHP Questions

72. How can you check whether the value of the given variable is number or not?

We can use is_numeric for checking whether they are number or not.

73. What function can be used in determining whether a file exists?

feof(), is_readable(), file_exists(), is_file_exists()

74. Which of the following is not a valid Simple XML Parser method?

• simplexml_import_dom()
• simplexml_import_sax()
• simplexml_load_file()
• simplexml_load_string()
• The function simplexml_import_sax() is not valid.

75. How objects are passed either by reference or value?

When passing objects to functions in programming languages, there are two primary mechanisms: pass by value and pass by reference. The choice between these methods can significantly impact how the original object is modified within the function.

Pass by Value

A copy of the object is created and passed to the function in pass-by value. This means any changes made to the object within the function do not affect the original object.

Example: Python def modify_object(obj):

obj.property = “new value”

my_object = {“property”: “old value”}

modify_object(my_object)

print(my_object[“property”]) # Output: “old value”

In this example, modify_object is passed a copy of my_object. The modification within the function doesn’t affect the original my_object.

76. How to pass variable by value?

We can put the “&” Ampersand in front of the value.

What is the query for displaying the top 20 rows?

Select* From table_name Limit 0 -20;

77. Define the Associative Array.

The Array with Strings as an index is known as an associative array.

78. From the below statements which of the following would produce the value of “83” as their output?

• echo intval(“0123”, 8);
• echo intval(“0123”);
• echo (int) 083
• echo intval(“0123”, 8); will produce 83 as their output.

It is one of the most often requested PHP And Mysql Interview Questions.

79. Define Multidimensional Array.

An Array which contains more than 1 array is called a Multidimensional array. Also, the values can be accessed using various indices.

80. Elucidate SQL Injection?

The SQL injection is code injection technique. It is used in attacking data-driven applications

81. From the below cURL which of them is not a valid parameter PHP?

• CURLOPT_RETURNTRANSFER, CURLOPT_GET, CURLOPT_POST
• CURLOPT_RETURNTRANSFER is not the valid cURL.

82. Name the functions that are used for searching the strings using the POSIX-style regular expression?

• sql_regcase(), eragi_replace(), ereg_replace(), spliti(), erag()
• sql_regcase() and ereg_replace() functions are used.

83. How can we sort array in the reverse order?

By using “ksort”.

To succeed in the interview, thoroughly prepare for these PHP interview questions and answers.

PHP Interview Questions For Experienced Developers

84. What is the role of MySQL check?

It is a Client program that is used to check the integrity of the database tables.

85. What is TimeStamp?

They are the data type that can show the automatically generated binary numbers. The timestamp is used as the mechanism for the version of stamping table rows.

86. Mention the advantages of the InnoDB over MyISAM.

The Advantages include:

• Transactions
• Row-level locking
• Crash Recovery
• Foreign key Constraints.

87. Which one is not a valid method in PHP XML DOM?

• geElementByName(), removeChild(), geElementById(), appendChild()
• geElementById() is not a valid method in the PHP XML DOM.

88. What is the role of a LAMP in PHP?

It is a combination of Linux, Apache, PHP, and MySQL.

89. What is the meaning of Self in PHP?

It is the Self keyword that is used in accessing the static methods and properties.

You can have a thorough understanding of the topic before the interview by reading these PHP Basic Interview Questions.

90. Explain MySQL dump.

This is the client program, and it creates logical database backups.

91. What is the Scope level in PHP?

Private, Public, Protected

92. What is the limit of the identifiers in MySQL?

Table 64bytes, Index 64 bytes, Column 64 bytes, Database 64 bytes, Alias 255 bytes

93. How can we identify the current session ID?

session_id()

94. Can PHP support different inheritances?

No, PHP supports single inheritance but allows multiple inheritance-like behaviors using traits and interfaces.

95. What are the various types of operators available in PHP?

Union, Union All, Minus, Intersect

96. Explain White Box Testing.

It deals with tables, schema, data models, and referential integrity rules. They also deal with a logical view supporting database consistency, triggers, and ACID properties.

The most common concept in Core PHP Interview Questions is pointers in PHP.

97. What is Elucidate CTE?

Common Table Expression consists of a temporary set of results, which are defined in the SQL statement.

98. List the encryption functions that are available in PHP.

crypt(), Mcrypt(), hash()

99. What are the various types of print functions that are available in PHP?

print() Function, printf() Function, echo() Function, print_r() Function, sprintf() Function

100. Explain Composer in PHP.

It is the package manager for the application level in PHP. Composer permits you to declare libraries depending on the project and also allows you to update them.

101. What is an action attribute in the HTML form?

It determines the place where to send a form data on the form submission.

102. How would you protect the special characters in the query string?

We can protect using urlencode() function.

103. What is Exception::getmessage?

It permits us to receive the Exception message.

104. How would you remove the white space from the start till the end of the $string variable?

We can use trim($string);

105. Mention the default time session in PHP.

The default time for a PHP session is 24 minutes or 1440 seconds. After an inactive login session has been idle for more than the defined time, PHP marks it as garbage and deletes the session file through its garbage collection process.

If you’re preparing for a PHP interview, be sure to review these PHP Interview Questions For Experienced.

106. Differentiate between PHP and Java

107. Differentiate between HTML and PHP

108. Elucidate polymorphism in PHP

It describes patterns in object-oriented programming where the classes have multiple functionality when sharing the common interface.

109. Mention the use of die in PHP

This function prints the message and exists in the current script.

110. Write the syntax of the mail() function in PHP

mail($to,$subject,$message,$headers)

It is one of the Core PHP Interview Questions that is regularly asked.

111. List the general MYSQL functions

NOWO, CURRDATEO, CONCAT (X, Y), DATEDIFF (X, Y)

Note: These are just some of the many PHP and MySQL interview questions that can be asked. The specific questions you may encounter will depend on your experience level and the role you are applying for.

In the coming days, we will add the number of Interview Questions to this blog. For more details regarding PHP and MySQL refer to our website.

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