Count records from multiple tables in real-time - php

Question

I want to count a record by current date from different tables and return as one row with different column in the new table. The code will update a record every three hours and insert new record if current date changes. I've current date and time data (2013-05-20 14:12:12) in "created_at" column. Here my current code:
require_once('./db_connect.php');
$dbcon = new db;
//test to see if a specific field value is already in the DB
public function in_table($table,$where) {
$query = 'SELECT * FROM ' . $table . ' WHERE ' . $where;
$result = mysqli_query($this->dbh,$query);
$this->error_test('in_table',$query);
return mysqli_num_rows($result) > 0;
}
//running in background
while (true) {
$select= "SELECT (SELECT CURDATE()) AS time," .
"(SELECT COUNT(tweet_id) FROM tweets WHERE created_at= 'CURDATE() %') AS total_count," .
"(SELECT COUNT(fid) FROM fun WHERE ftime= 'CURDATE() %') AS f_count," .
"(SELECT COUNT(sid) FROM sad WHERE stime= 'CURDATE() %') AS s_count";
$results = mysqli_query( $dbcon, $select );
while($row = mysqli_fetch_assoc($result)) {
$time = $row['time'];
$total = $row['total_count'];
$fcount = $row['f_count'];
$scount = $row['s_count'];
$field_values = 'time = "' . $time . '", ' . 'total_count = ' . $total . ', ' . 'fun_count = ' . $fcount . ', ' . 'sad_count = ' . $scount;
if ($dbcon->in_table('count','time= "' . $time . '"')) {
$update = "UPDATE count SET $field_values WHEN time= '$time'";
mysqli_query( $dbcon, $update );
}
else {
$insert = "INSERT INTO count SET $field_values";
mysqli_query( $dbcon, $insert );
}
}
//update record every 3 hour
sleep(10800);
}
With this code I can't get a count record. The result return | 2013-05-18 | 0 | 0 | 0 |. How can I correct this?

Answer 1

I not familiar with PHP, but you can retrieve the count of all records dated any time today using:
SELECT COUNT(tweet_id)
FROM tweets
WHERE created_at >= curDate()
AND created_at < date_add(curDate(), interval 1 day)
It is equivalent to saying
..
WHERE created_at >= (today at midnight *incusive*)
AND created_at < (tomorrow at midnight *exclusive*)
Update:
The advantage of this method is it is index friendly. While using WHERE DATE(Column) = currDate() works, it can prevent the database from using indexes on that column, making the query slower.

Answer 2

Replace the parts where you have this:
WHERE created_at= 'CURDATE() %'
with this:
WHERE DATE(created_at) = CURDATE()
Your existing WHERE clause is comparing created_at to the string constant CURDATE() %, and they'll never match.

Answer 3

You are comparing against created_at= 'CURDATE() %', which is looking for that exact string, not for the result of a function. If the field created_at is a date, it will never match.
And, you are doing that for all counts.