Prepare 4 interview - Recent questions and answers in MySQL Interview Questions and Answers

Answered: If you specify the data type as DECIMAL (5,2), what’s the range of values that can go in this table?

Sun, 27 Nov 2011 14:59:55 +0000

Do you know http://it-how.com ?

Answered: If I created a column with data type VARCHAR(3), what would I expect to see in MySQL table?

Mon, 27 Sep 2010 13:42:37 +0000

CHAR(3), since MySQL automatically adjusted the data type.

Answered: Explain TIMESTAMP DEFAULT ‘2006:09:02 17:38:44′ ON UPDATE CURRENT_TIMESTAMP.

Mon, 27 Sep 2010 13:37:06 +0000

A default value is used on initialization, a current timestamp is inserted on update of the row.

Answered: What does TIMESTAMP ON UPDATE CURRENT_TIMESTAMP data type do?

Mon, 27 Sep 2010 13:36:09 +0000

On initialization places a zero in that column, on future updates puts the current value of the timestamp in.

Answered: Explain data type TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP

Mon, 27 Sep 2010 13:35:25 +0000

The column exhibits the same behavior as a single timestamp column in a table with no other timestamp columns.

Answered: What if you really want to store the timestamp data, such as the publication date of the article?

Mon, 27 Sep 2010 13:34:08 +0000

Create two columns of type TIMESTAMP and use the second one for your real data.

Answered: What happens if a table has one column defined as TIMESTAMP?

Mon, 27 Sep 2010 13:31:55 +0000

That field gets the current timestamp whenever the row gets altered.

Answered: Explain the difference between FLOAT, DOUBLE and REAL.

Mon, 27 Sep 2010 13:13:50 +0000

FLOATs store floating point numbers with 8 place accuracy and take up 4 bytes. DOUBLEs store floating point numbers with 16 place accuracy and take up 8 bytes. REAL is a synonym of FLOAT for now.

Answered: Explain the difference between BOOL, TINYINT and BIT.

Mon, 27 Sep 2010 13:13:05 +0000

Prior to MySQL 5.0.3: those are all synonyms. After MySQL 5.0.3: BIT data type can store 8 bytes of data and should be used for binary data.

Answered: What happens when the column is set to AUTO INCREMENT and you reach the maximum value for that table?

Mon, 27 Sep 2010 13:12:17 +0000

It stops incrementing. It does not overflow to 0 to prevent data losses, but further inserts are going to produce an error, since the key has been used already.

Answered: What is SERIAL data type in MySQL?

Mon, 27 Sep 2010 13:11:04 +0000

BIGINT NOT NULL PRIMARY KEY AUTO_INCREMENT

Answered: Explain federated tables.

Mon, 27 Sep 2010 13:10:21 +0000

Introduced in MySQL 5.0, federated tables allow access to the tables located on other databases on other servers.

Answered: What are CSV tables?

Mon, 27 Sep 2010 13:09:16 +0000

Those are the special tables, data for which is saved into comma-separated values files. They cannot be indexed.

Answered: How do you control the max size of a HEAP table?

Mon, 27 Sep 2010 13:08:21 +0000

MySQL config variable max_heap_table_size.

Answered: What are HEAP tables in MySQL?

Mon, 27 Sep 2010 13:07:20 +0000

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_INCREMENT. Indexes must be NOT NULL.

Answered: Explain advantages of MyISAM over InnoDB?

Mon, 27 Sep 2010 13:05:13 +0000

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 not 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.

Answered: Explain advantages of InnoDB over MyISAM?

Mon, 27 Sep 2010 13:04:34 +0000

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

Answered: What does myisamchk do?

Mon, 27 Sep 2010 13:03:59 +0000

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

Answered: Explain the difference between MyISAM Static and MyISAM Dynamic.

Mon, 27 Sep 2010 13:03:21 +0000

In MyISAM static all the fields have fixed width. The Dynamic MyISAM table 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.

Answered: What are some good ideas regarding user security in MySQL?

Mon, 27 Sep 2010 13:02:30 +0000

There is no user without a password. There is no user without a user name. There is no user whose Host column contains % (which here indicates that the user can log in from anywhere in the network or the Internet). There are as few users as possible (in the ideal case only root) who have unrestricted access.

Have you ever used MySQL Administrator and MySQL Query Browser?

Mon, 27 Sep 2010 13:01:53 +0000

Answered: Use mysqldump to create a copy of the database?

Mon, 27 Sep 2010 13:01:21 +0000

mysqldump -h mysqlhost -u username -p mydatabasename > dbdump.sql

Answered: How do you change a password for an existing user via mysqladmin?

Mon, 27 Sep 2010 13:00:38 +0000

mysqladmin -u root -p password "newpassword"

Answered: Can you save your connection settings to a conf file?

Mon, 27 Sep 2010 12:59:48 +0000

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.

Answered: What does tee command do in MySQL?

Mon, 27 Sep 2010 12:58:56 +0000

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

Answered: What’s the default port for MySQL Server?

Mon, 27 Sep 2010 12:58:14 +0000

What’s the default port for MySQL Server?
3306

Answered: Explain the difference between mysql and mysqli interfaces in PHP?

Mon, 27 Sep 2010 12:57:00 +0000

mysqli is the object-oriented version of mysql library functions.

Answered: How do you start MySQL on Linux?

Mon, 27 Sep 2010 12:56:00 +0000

/etc/init.d/mysql start

Answered: How do you start and stop MySQL on Windows?

Mon, 27 Sep 2010 12:54:42 +0000

net start MySQL, net stop MySQL

Tell something about MySQL

Sat, 19 Jun 2010 20:42:33 +0000

MySQL

MySQL is open source SQL database, which is developed by Swedish company MySQL AB. MySQL is pronounced "my ess-que-ell," in contrast with SQL, pronounced "sequel."

MySQL is supporting many different platforms including Microsoft Windows, the major Linux distributions, UNIX, and Mac OS X.

MySQL has free and paid versions, depending on its usage (non-commercial/commercial) and features. MySQL comes with a very fast, multi-threaded, multi-user, and robust SQL database server.

History:

Development of MySQL by Michael Widenius & David Axmark beginning in 1994.

First internal release on 23 May 1995.

Windows version was released on 8 January 1998 for Windows 95 and NT.

Version 3.23: beta from June 2000, production release January 2001.

Version 4.0: beta from August 2002, production release March 2003 (unions).

Version 4.01: beta from August 2003, Jyoti adopts MySQL for database tracking.

Version 4.1: beta from June 2004, production release October 2004.

Version 5.0: beta from March 2005, production release October 2005.

Sun Microsystems acquired MySQL AB on 26 February 2008.

Version 5.1: production release 27 November 2008.

Features:

High Performance.

High Availability.

Scalability and Flexibility Run anything.

Robust Transactional Support.

Web and Data Warehouse Strengths.

Strong Data Protection.

Comprehensive Application Development.

Management Ease.

Open Source Freedom and 24 x 7 Support.

Lowest Total Cost of Ownership.