Question : how do I count the number of rows in my db

Hi,

how do I count the number of rows in my db where columnA = test ? .. I need the number in a variable to do other calculations.

mySQL & PHP

thanks.

Answer : how do I count the number of rows in my db

It's not practical to try to count the number of rows in the DB, but to count the number of rows in a TABLE named "my_table" you can use a script like this.
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<?php // RAY_mysql_example.php
error_reporting(E_ALL);


// IMPORTANT PAGES FROM THE MANUALS
// MAN PAGE: http://us2.php.net/manual/en/ref.mysql.php
// MAN PAGE: http://us2.php.net/manual/en/mysql.installation.php
// MAN PAGE: http://us.php.net/manual/en/function.mysql-error.php


// CONNECTION AND SELECTION VARIABLES FOR THE DATABASE
$db_host = "localhost"; // PROBABLY THIS IS OK
$db_name = "??";        // GET THESE FROM YOUR HOSTING COMPANY
$db_user = "??";
$db_word = "??";

// OPEN A CONNECTION TO THE DATA BASE SERVER
// MAN PAGE: http://us2.php.net/manual/en/function.mysql-connect.php
if (!$db_connection = mysql_connect("$db_host", "$db_user", "$db_word"))
{
   $errmsg = mysql_errno() . ' ' . mysql_error();
   echo "<br/>NO DB CONNECTION: ";
   echo "<br/> $errmsg <br/>";
}

// SELECT THE MYSQL DATA BASE
// MAN PAGE: http://us2.php.net/manual/en/function.mysql-select-db.php
if (!$db_sel = mysql_select_db($db_name, $db_connection))
{
   $errmsg = mysql_errno() . ' ' . mysql_error();
   echo "<br/>NO DB SELECTION: ";
   echo "<br/> $errmsg <br/>";
   die('NO DATA BASE');
}
// IF WE GOT THIS FAR WE CAN DO QUERIES




// ESCAPING A DATA FIELD FOR USE IN MYSQL QUERIES
// MAN PAGE: http://us2.php.net/manual/en/function.mysql-real-escape-string.php
$safe_test = mysql_real_escape_string('test');




// CREATING AND SENDING A SELECT QUERY AND TESTING THE RESULTS
// MAN PAGE:http://us2.php.net/manual/en/function.mysql-query.php
$sql = "SELECT columnA FROM my_table WHERE columnA = '$safe_test'";
$res = mysql_query($sql);

// IF mysql_query() RETURNS FALSE, GET THE ERROR REASONS
// MAN PAGE: http://us.php.net/manual/en/function.mysql-error.php
if (!$res)
{
   $errmsg = mysql_errno() . ' ' . mysql_error();
   echo "<br/>QUERY FAIL: ";
   echo "<br/>$sql <br/>";
   die($errmsg);
}
// IF WE GET THIS FAR, THE QUERY SUCCEEDED AND WE HAVE A RESOURCE-ID IN $res SO WE CAN NOW USE $res IN OTHER MYSQL FUNCTIONS




// DETERMINE HOW MANY ROWS OF RESULTS WE GOT
// MAN PAGE: http://us2.php.net/manual/en/function.mysql-num-rows.php
$num = mysql_num_rows($res);
if (!$num)
{
   echo "<br/>QUERY FOUND NO DATA: ";
   echo "<br/>$sql <br/>";
}
else
{
   echo "<br/>QUERY FOUND $num ROWS OF DATA ";
   echo "<br/>$sql <br/>";
}
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