如何在MySQL或PHP上根据日期对输出行进行分组？

Question

The following query returns some rows, that each one has its own date_created .

SELECT *
FROM   table1 l 
       inner join table2 d 
               ON d.id = l.id 
WHERE  l.company_id = 1

UNION ALL 

SELECT * 
FROM   table1 l 
       inner join table3 p 
               ON p.id = l.id 
WHERE  p.company_id = 1

sample output:

company_id ---- user_id ---- text ---- dateAndTime
1          ----  abc    ----  hi  ---- 2017-08-17 22:26:18
1          ----  def    ----  hey ---- 2017-08-08 11:57:26
1          ----  abc    ----  hi  ---- 2017-08-08 11:55:40
1          ----  ghz    ----  sup ---- 2017-07-25 16:01:34

What I want to achieve:

I am running a php foreach loop to display all of these data. However on each date change, I want to display the date (like groupping them design-wise).

So the output (on display)

2017-08-17
    1          ----  abc    ----  hi  ---- 2017-08-17 22:26:18
2017-08-08
    1          ----  def    ----  hey ---- 2017-08-08 11:57:26
    1          ----  abc    ----  hi  ---- 2017-08-08 11:55:40
2017-07-25
    1          ----  ghz    ----  sup ---- 2017-07-25 16:01:34

How can I achieve this either with mySQL or PHP?

Answer 1

Store the last date in a variable, check in every iteration:

$q = "SELECT company_id, user_id, text, dateAndTime, DATE(dateAndTime) as date FROM   table1 l inner join table2 d ON d.id = l.id WHERE  l.company_id = 1 UNION ALL SELECT company_id, user_id, text, dateAndTime, DATE(dateAndTime) as date FROM   table1 l inner join table3 p ON p.id = l.id WHERE  p.company_id = 1";
// ...
$lastGroupDate = null;
foreach ($row as $company) {
    if ($lastGroupDate !== $company["date"]) {
        echo $company["date"]."<br>";
    }
    echo $company["user_id"]."<br>";
    // rest of fields
    $lastGroupDate = $company["date"];
}

Remember to sort the results by dateAndTime in the query.

Important: you need to get DATE(dateAndTime) as date in the query too, since you need to group them by only date (not time).