将两个查询合并为一个而不循环mysql

Question

how to join this in single query any help to combine these two queries as one without looping,

$today_date = mktime(0, 0, 0, $mon, $day-1, $year);

SELECT *  FROM (`lead_follow_up`) LEFT JOIN `leads` ON `leads`.`id` = `lead_follow_up`.`lead_id` WHERE `date` <=  $today_date GROUP BY `lead_follow_up`.`lead_id` ORDER BY `lead_follow_up`.`date` DESC
from the above query i get array $previou



$previou=    Array
(
    [0] => stdClass Object
        (
            [id] => 1
            [lead_id] => 75943
            [date] => 1438930800
            [updated_on] => 1438884890
        )

    [1] => stdClass Object
        (
            [id] => 2
            [lead_id] => 75943
            [date] => 1416459600
            [updated_on] => 1415901523
        ),
     [2] => stdClass Object
        (
            [id] => 3
            [lead_id] => 75943
            [date] => 1416459600
            [updated_on] => 1415901523
        ),....etc

);

foreach($previou as $key => $p):
    $q = "SELECT `id` FROM (`lead_follow_up`) WHERE `lead_id` = '".$p->id."' AND `date` > '".$p->date."' ORDER BY `updated_on` DESC ";
    if(!$this->db->query($q)){
        $previouData[$key] = $p;
        $pCount++;
    }
endforeach;

how to join this in single query any help to combine these two queries as one without looping,

Answer 1

Your queries don't make much sense. For a start your first query has a GROUP BY lead_follow_up . lead_id but no aggregate functions. So in MySQL that will return one row for each value of lead_id (which row it returns is not defined).

Yet your array of sample data has multiple rows per lead_id so cannot have come from the query.

You are also LEFT OUTER JOINing the leads table, yet it doesn't seem to make sense to have a lead_follow_up which doesn't relate to a lead. As such you may as well use an INNER JOIN.

I am going to assume that what you want is a list of leads / lead_follow_ups and for each one a couple of all the follow ups after that particular follow up. That would give you something like this (making loads of assumptions as I do not know your table structure):-

SELECT leads.id AS lead_id,
        lead_follow_up.id
        lead_follow_up.`date`,
        lead_follow_up.updated_on,
        COUNT(lead_follow_up_future.id) AS future_lead_count
FROM leads 
INNER JOIN lead_follow_up ON leads.id = lead_follow_up.lead_id 
LEFT OUTER JOIN lead_follow_up AS lead_follow_up_future ON leads.id = lead_follow_up.lead_id AND lead_follow_up_future.`date` > lead_follow_up.`date` 
WHERE lead_follow_up.`date` <=  $today_date 
GROUP BY leads.id AS lead_id,
        lead_follow_up.id
        lead_follow_up.`date`,
        lead_follow_up.updated_on
ORDER BY lead_follow_up.date DESC