Frequently asked MySQL interview questions

Frequently asked mysql intrview questions

1. How can we create a database using PHP and mysql?

We can create MySQL database with the use of mysql_create_db(“Database_Name”) or $sql = 'CREATE DATABASE `database_name`'; if (mysql_query($sql, $link))      echo “Database my_db created successfully\n”; else       echo ‘Error creating database: ‘ . mysql_error() . “\n”;

2. What are the different tables present in mysql, which type of table is generated when we are creating a table in the following syntax: create table employee(eno int(2),ename varchar(10)) ?

Total 5 types of tables we can create 1. ISAM (Index Sequential Access Method) 2. MyISAM    o Static    o Dynamic    o Compress 3. Heap (Fastest tables because it stores in to the RAM. It is ideal if you need a small amount of     fast but temporary local table space) 4. Merge ( allows to combine several other tables into a single logical table) 5. INNO DB (Transaction safe table) 6. BDB ( berkelyeyDB) MyISAM is the default storage engine as of MySQL 3.23.

3. What are the current versions of apache, PHP, and mysql?

For information about latest version of Apache, Php and Mysql please visits the following sites respectively: http://www.apache.org/ http://www.php.net/ http://www.mysql.com/

4. How can we optimize or increase the speed of a mysql select query?

First, one thing that affects all queries: The more complex permission system setup you have, the more overhead you get. If you do not have any GRANT statements done, MySQL will optimise the permission checking somewhat. So if you have a very high volume it may be worth the time to avoid grants. Otherwise, more permission check results in a larger overhead.

5. How can we change the name and data type of a column of a table ?

$sql = 'ALTER TABLE `webprogrammer` CHANGE `duration` `durations` INT(30) NOT NULL';

6. What are the differences between drop a table and truncate a table

drop a table command, drops a full table ( deletes structure and table data )truncate table deletes data only, and keeps the structure alive. Drop: "DROP TABLE table_name" Truncate: "TRUNCATE TABLE table_Name"

7. A select query over a large table runs very slow because of the growing number of entries in that table. What different measures could be taken to improve speed? or How can we increase the speed of a mysql select query? or How can increase the performance of mysql select query?

should on indexed field,generally using primarykey. or using "Index" fileds.

8. What is meant by MIME

Multipurpose Internet Mail Extensions or MIME is Multipurpose Internet Mail Extensions is an internet standard for the format of e-mail. Howewer browsers also uses MIME standart to transmit files. MIME has a header wich is added to a begining of the data. When browser sees such header it shows the data as it would be a file (for example image) some mimes: audio/x-ms-wmp image/png aplication/x-shockwave-flash