counting entries in table

[Anon]

I am looking for the best/most effiecient way to do the following:

a) count the entries in a table
b) display the last 5 lines starting with the last line.

I know ways of doing this, but as these tables will be growing to upwards of a thousand entries, I am looking for the most efficient way of doing this.

Thanks for the input!

-Mike

[[deleted]]

Assuming you are using MySQL:

a) Read the manual: SELECT count() FROM table;
b) Put an auto_increment column in your table, and SELECT FROM table ORDER BY ID desc LIMIT 5;

[Anon]

The equivalent of auto_increment in PostgreSQL is the type "serial". For any database, ensure the column is indexed for fast sort.

[williamjames]

This Small Snipit of code I modified from a friend. It will list the last 5 results from a mysql querry.
<?php
$link = mysql_pconnect ("kron", "jutta", "geheim")
or die ("Could not connect");

mysql_select_db ("samp_db")
    or die ("Could not select database");

$query = "SELECT last_name, first_name FROM friends";
$result = mysql_query ($query)
    or die ("Query failed");

# fetch rows in reverse order

$s = $result - 4;
for ($i = mysql_num_rows ($result) - 1; $i >=$s; $i--) {
if (!mysql_data_seek ($result, $i)) {
printf ("Cannot seek to row %d\n", $i);
continue;
}

    if(!($row = mysql_fetch_object ($result)))
        continue;

    printf ("%s %s<BR>\n", $row->last_name, $row->first_name);
}

mysql_free_result ($result);

?>

[[deleted]]

This works, but it's not what you want.
This snippet simply fetches all rows, and only prints the last 5 rows.
What you want is a query that only fetches the last five rows in the first place.