PHP INTERVIEW QUESTIONS 60-70

61. What are the other commands to know the structure of table using MySQL commands except explain command?

DESCRIBE table_name;

62. How many tables will create when we create table, what are they?

If you create one table ,  then only one table with be created. 
But 3 files with be created namely tb_name.frm,tb_name.myi,tb_name.myd,

1. Data is stored in name.myd
2. Table structure is stored in name.frm
3. Index is stored in name.myi

63. What is the purpose of the following files having extensions 1) .frm 2) .myd 3) .myi? What do these files contain?

1. Data is stored in name.myd
2. Table structure is stored in name.frm
3. Index is stored in name.myi

64. What is maximum size of a database in MySQL?

If the operating system or filesystem places a limit on the number of files in a directory,
MySQL is bound by that constraint. The efficiency of the operating system in handling large
numbers of files in a directory can place a practical limit on the number of tables in a
database. If the time required to open a file in the directory increases significantly as
the number of files increases, database performance can be adversely affected.
The amount of available disk space limits the number of tables.
MySQL 3.22 had a 4GB (4 gigabyte) limit on table size. With the MyISAM storage engine
in MySQL 3.23, the maximum table size was increased to 65536 terabytes (2567 – 1 bytes).
With this larger allowed table size, the maximum effective table size for MySQL databases is
usually determined by operating system constraints on file sizes, not by MySQL internal
limits.
The InnoDB storage engine maintains InnoDB tables within a tablespace that can be created
from several files. This allows a table to exceed the maximum individual file size.
The tablespace can include raw disk partitions, which allows extremely large tables.
The maximum tablespace size is 64TB.
The following table lists some examples of operating system file-size limits.
This is only a rough guide and is not intended to be definitive. For the most up-to-date
information, be sure to check the documentation specific to your operating system.
Operating System File-size Limit
Linux 2.2-Intel 32-bit 2GB (LFS: 4GB)
Linux 2.4+ (using ext3 filesystem) 4TB
Solaris 9/10 16TB
NetWare w/NSS filesystem 8TB
Win32 w/ FAT/FAT32 2GB/4GB
Win32 w/ NTFS 2TB (possibly larger)
MacOS X w/ HFS+ 2TB  

65. Give the syntax of Grant and Revoke commands?         
grant all on table_name to user_name; 
Revoke all on table_name from user_name;
GRANT [rights] on [database/s] TO [username@hostname] IDENTIFIED BY [password] All
privileges

REVOKE [rights] on [database/s] FROM [username@hostname] All privileges    

66. Explain Normalization concept?   
The normalization process involves getting our data to conform to three progressive normal
forms, and a higher level of normalization cannot be achieved until the previous levels have
been achieved (there are actually five normal forms, but the last two are mainly academic
and will not be discussed).

First Normal Form
The First Normal Form (or 1NF) involves removal of redundant data from horizontal rows.
We want to ensure that there is no duplication of data in a given row, and that every column
stores the least amount of information possible (making the field atomic).

Second Normal Form
Where the First Normal Form deals with redundancy of data across a horizontal row,
Second Normal Form (or 2NF) deals with redundancy of data in vertical columns.
As stated earlier, the normal forms are progressive, so to achieve Second Normal Form,
your tables must already be in First Normal Form.

Third Normal Form

I have a confession to make; I do not often use Third Normal Form.
In Third Normal Form we are looking for data in our tables that is not fully dependant
on the primary key, but dependant on another value in the table 

67.How can we find the number of rows in a table using MySQL?

Mysql : - select count(*) [tablename]; PHP :- mysql_num_rows(); 

68. How can we find the number of rows in a result set using PHP?

mysql_num_rows($rs) 

69. How many ways we can we find the current date using MySQL?

CURRENT_DATE() now() CURDATE( ) 

70. What are the advantages and disadvantages of Cascading Style Sheets?

Advantages of CSS:
1. CSS saves time:
When most of us first learn HTML, we get taught to set the font face, size, colour, style etc every time it occurs on a page. This means we find ourselves typing (or copying & pasting) the same thing over and over again. With CSS, you only have to specify these details once for any element. CSS will automatically apply the specified styles whenever that element occurs.
2. Pages load faster
Less code means faster download times.
3. Easy maintenance
To change the style of an element, you only have to make an edit in one place.
4.Superior styles to HTML
CSS has a much wider array of attributes than HTML.
Disadvantages of CSS:

1.Browsercompatibility

Browsers have varying levels of compliance with Style Sheets. This means that some Style Sheet features are supported and some aren't. To confuse things more, some browser manufacturers decide to come up with their own proprietary tags.