Skip to main content
There are three informations, which you would like to have from MySQL.
  • Information about the result of queries: This includes number of records affected by any SELECT, UPDATE or DELETE statement.
  • Information about tables and databases: This includes information pertaining to the structure of tables and databases.
  • Information about the MySQL server: This includes current status of database server, version number etc.
It's very easy to get all these information at mysql prompt, but while using PERL or PHP APIs, we need to call various APIs explicitly to obtain all these information. Following section will show you how to obtain this information.

Obtaining the Number of Rows Affected by a Query:

PERL Example:

In DBI scripts, the affected-rows count is returned by do( ) or by execute( ), depending on how you execute the query:
# Method 1
# execute $query using do( )
my $count = $dbh->do ($query);
# report 0 rows if an error occurred
printf "%d rows were affected\n", (defined ($count) ? $count : 0);

# Method 2
# execute query using prepare( ) plus execute( )
my $sth = $dbh->prepare ($query);
my $count = $sth->execute ( );
printf "%d rows were affected\n", (defined ($count) ? $count : 0);

PHP Example:

In PHP, invoke the mysql_affected_rows( ) function to find out how many rows a query changed:
$result_id = mysql_query ($query, $conn_id);
# report 0 rows if the query failed
$count = ($result_id ? mysql_affected_rows ($conn_id) : 0);
print ("$count rows were affected\n");

Listing Tables and Databases:

This is very easy to list down all the databases and tables available with database server. Your result may be null if you don't have sufficient privilege.
Apart from the method I have mentioned below, you can use SHOW TABLES or SHOW DATABASES queries to get list of tables or databases either in PHP or in PERL.

PERL Example:

# Get all the tables available in current database.
my @tables = $dbh->tables ( );
foreach $table (@tables ){
   print "Table Name $table\n";
}

PHP Example:

<?php
$con = mysql_connect("localhost", "userid", "password");
if (!$con)
{
  die('Could not connect: ' . mysql_error());
}

$db_list = mysql_list_dbs($con);

while ($db = mysql_fetch_object($db_list))
{
  echo $db->Database . "<br />";
}
mysql_close($con);
?>

Getting Server Metadata:

There are following commands in MySQL which can be executed either at mysql prompt or using any script like PHP to get various important informations about database server.
CommandDescription
SELECT VERSION( )Server version string
SELECT DATABASE( )Current database name (empty if none)
SELECT USER( )Current username
SHOW STATUSServer status indicators
SHOW VARIABLESServer configuration variables

Comments

Popular posts from this blog

Android operating system is a stack of software components which is roughly divided into five sections and four main layers as shown below in the architecture diagram. Linux kernel At the bottom of the layers is Linux - Linux 3.6 with approximately 115 patches. This provides a level of abstraction between the device hardware and it contains all the essential hardware drivers like camera, keypad, display etc. Also, the kernel handles all the things that Linux is really good at such as networking and a vast array of device drivers, which take the pain out of interfacing to peripheral hardware. Libraries On top of Linux kernel there is a set of libraries including open-source Web browser engine WebKit, well known library libc, SQLite database which is a useful repository for storage and sharing of application data, libraries to play and record audio and video, SSL libraries responsible for Internet security etc. Android Libraries This category encompasses those Java-based li
C is a general-purpose, procedural, imperative computer programming language developed in 1972 by Dennis M. Ritchie at the Bell Telephone Laboratories to develop the UNIX operating system. C is the most widely used computer language. It keeps fluctuating at number one scale of popularity along with Java programming language, which is also equally popular and most widely used among modern software programmers. Audience This tutorial is designed for software programmers with a need to understand the C programming language starting from scratch. This tutorial will give you enough understanding on C programming language from where you can take yourself to higher level of expertise. Prerequisites Before proceeding with this tutorial, you should have a basic understanding of Computer Programming terminologies. A basic understanding of any of the programming languages will help you in understanding the C programming concepts and move fast on the learning track. Execute
C is a general-purpose, high-level language that was originally developed by Dennis M. Ritchie to develop the UNIX operating system at Bell Labs. C was originally first implemented on the DEC PDP-11 computer in 1972. In 1978, Brian Kernighan and Dennis Ritchie produced the first publicly available description of C, now known as the K&R standard. The UNIX operating system, the C compiler, and essentially all UNIX application programs have been written in C. C has now become a widely used professional language for various reasons − Easy to learn Structured language It produces efficient programs It can handle low-level activities It can be compiled on a variety of computer platforms Facts about C C was invented to write an operating system called UNIX. C is a successor of B language which was introduced around the early 1970s. The language was formalized in 1988 by the American National Standard Institute (ANSI). The UNIX OS was totally written in C. Today C