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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Mysql and PHP Interview Questions

Top ten Interview Question

1.       What is the difference between sql and mysql?

2.       What is the difference between print and echo in PHP?

3.       What is the difference between superkey candidate  and primary keys?

4.       How to send mail using MSSQL  Express edition?

5.       What is meant by Exception Handling ?

6.       What is difference between mysql_fetch_object and mysql_fetch_array?

7.       How can we submit a form without a submit button?

8.       What is the difference between GET and POST method?

9.       What is the difference between strstr() and stristr()?

10.   What is the maximum length for database, table & column name?

PHP Interview for Fresher Job

PHP Interview Question

1.       What is difference between include and require?

2.       What is difference between session and cookies?

3.       How do you create a cookie , add data to it and remove data from a cookie?

4.       How do you create a session, add data to a session and remove data from a   session?

5.       If cookies are displayed will the sessions work? Why?

6.       What is the difference between a framework, IDE, CMS, blog?

7.       What is the difference between $var and $$var?

8.       If a form does not have submit button, how do you submit a form?

9.       Write a function to calculate x to the power y without using the pow function of PHP?

10.   What is the difference between client side validation and serve side validation and what is more secure and why?

Tutorial of Session

Session Class

The session class allows you to maintain a user's state as they browse your website. The session Class stores data inside a cookie, which can optionally be encrypted. You are able to store data inside a database for added security, as this means that the user's cookie must match the database record.

What is stored in a session?

-> the user's unique Session ID

-> The user's IP address

-> The user's User Agent string

-> The "last activity timestamp"

CodeIgniter library

A CodeIgniter library is simply a class file that abstracts functionality into easy to use functions that take much of the strain off the developers. Take the Database Library as an example. It contains many functions that make the creation of complex SQL queries very easy; it also makes queries much more readable.

CodeIgniter comes with many core libraries that provide ways to code your applications much faster than without libraries, removing much of the unnecessary code from your applications, and taking the strain off the developer.

CodeIgniter of MVC

What is (MVC) Model View Controller?

MVC is software development design pattern and MVC is an approach to separating your applications into three segments: Model, View, and Controllers. MVC structures your application in this way in order to promote the reuse of program code.

The model represents any type of data that you application may use. Some example of data that your application might use would be: a database, RSS Feeds, API calls and any other action that involves retrieving, returning, updating and removing data.

Views are the information that is being presented on the screen to users through their web browsers. These are usually HTML files, sometimes containing PHP code that builds the template for the website.

Finally Controllers are the business logic of your application. They serve as an intermediary between Models and views. The Controller will respond to HTTP requests and generate web pages.