What is MySQL?
MySQL is an open source DBMS which is built, supported and distributed by MySQL AB (now acquired by Oracle)
What are the technical features of MySQL?
MySQL database software is a client or server system which includes
Multithreaded SQL server supporting various client programs and libraries
Different backend
Wide range of application programming interfaces and
Administrative tools.
Why MySQL is used?
MySQL database server is reliable, fast and very easy to use. This software can be downloaded as freeware and can be downloaded from the internet.
What are Heap tables?
HEAP tables are present in memory and they are used for high speed storage on temporary
basis.
- BLOB or TEXT fields are not allowed
- Only comparison operators can be used =, <,>, = >,=<
- AUTO_INCREMENT is not supported by HEAP tables
- Indexes should be NOT NULL
What is the default port for MySQL Server?
The default port for MySQL server is 3306.
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What are the advantages of MySQL when compared with Oracle?
MySQL is open source software which is available at any time and has no cost involved.
MySQL is portable
GUI with command prompt.
Administration is supported using MySQL Query Browser
Differentiate between FLOAT and DOUBLE?
Following are differences for FLOAT and DOUBLE:
- Floating point numbers are stored in FLOAT with eight place accuracy and it has four bytes.
- Floating point numbers are stored in DOUBLE with accuracy of 18 places and it has eight bytes.
Differentiate CHAR_LENGTH and LENGTH?
CHAR_LENGTH is character count whereas the LENGTH is byte count. The numbers are same for Latin characters but they are different for Unicode and other encodings.
How to represent ENUMs and SETs internally?
ENUMs and SETs are used to represent powers of two because of storage optimizations.
What is the usage of ENUMs in MySQL?
ENUM is a string object used to specify set of predefined values and that can be used during table creation.
MySQL
Create table size(name ENUM(‘Small’, ‘Medium’,’Large’);
Who is the father of PHP and explain the changes in PHP versions?
Rasmus Lerdorf is known as the father of PHP.PHP/FI 2.0 is an early and no longer supported version of PHP. PHP 3
is the successor to PHP/FI 2.0 and is a lot nicer. PHP 4 is the current
generation of PHP, which uses the
Zend engine
under the
hood. PHP 5 uses
Zend engine 2 which,
among other things, offers many additionalOOP features
How can we submit a form without a submit button?
The main idea behind this is to use Java script submit() function in
order to submit the form without explicitly clicking any submit button.
You can attach the document.formname.submit() method to onclick,
onchange events of different inputs and perform the form submission. you
can even built a timer function where you can automatically submit the
form after xx seconds once the loading is done (can be seen in online
test sites).
In how many ways we can retrieve the data in the result set of
MySQL using PHP?
You can do it by 4 Ways1. mysql_fetch_row.
- mysql_fetch_array
- mysql_fetch_object
- mysql_fetch_assoc
How can we create a database using PHP and MySQL?
We can create MySQL database with the use of
mysql_create_db(“Database Name”)
Can we use include (”abc.PHP”) two times in a PHP page “makeit.PHP”?
Yes we can use include() more than one time in any page though it is
not a very good practice.
What storage engines are used in MySQL?
Storage engines are called table types and data is stored in files using various techniques.
Technique involves:
Storage mechanism
Locking levels
Indexing
Capabilities and functions.
What does a TIMESTAMP do on UPDATE CURRENT_TIMESTAMP data type?
TIMESTAMP column is updated with Zero when the table is created. UPDATE CURRENT_TIMESTAMP modifier updates the timestamp field to current time whenever there is a change in other fields of the table.
What is the difference between primary key and candidate key?
Every row of a table is identified uniquely by primary key. There is only one primary key for a table.
Primary Key is also a candidate key. By common convention, candidate key can be designated as primary and which can be used for any foreign key references.
How do you login to MySql using Unix shell?
We can login through this command:
# [mysqldir]/bin/mysql -h hostname -u <UserName> -p <password>
How do you control the max size of a HEAP table?
Maximum size of Heal table can be controlled by MySQL config variable called max_heap_table_size.
