How to check if name already in the table? Querying Mysql for sum of each day and then populating an HTML data through PHP with it

Question

So, this is my first question here, and I'd really appreciate if someone could help me. I currently have a Mysql database and a web app made with PHP where the users can input how much time they have used on a specific task that day.

Right now I would like to populate an HTML table with the SUM of each days activity in hours. My problem is that I can't find a way to check if the name field is unique, as the data contains many rows with the same name field, one for each day.

I have this Mysql query:

SELECT 
    t_email.name, 
    DATE_FORMAT(input_date,'%d') AS days, 
    SUM(time_worked) AS totalTime
FROM 
    t_transactions 
    LEFT JOIN t_email ON t_transactions.email_id >= t_email.email_id 
WHERE 
    DATE_FORMAT(input_date,'%m') = '02'
    AND DATE_FORMAT(input_date,'%Y') = '2019' 
GROUP BY DATE_FORMAT(input_date,'%d') 
ORDER BY t_email.name

Which returns me a table like this:

name  days  totalTime
james 01    5.00 
james 06    2.00 
jimmy 02    4.0

And so on. I'm using the below PHP:

<?php 
foreach ($monthly_data_per_day as $row): ?>
<tr>
    <td><?= $row['name'] ?></td>
    <?php
    $num_days = date('t');
    for ($i = 1; $i <= $num_days; $i++) {
        if ($row['days'] == $i) {
            echo "<td>" . $row['totalTime'] . "</td>";
        } else {
            echo "<td>" . 0 . "</td>";
        }
    }?></tr>
<?php endforeach;?>

I'd like to have an HTML table where after each name in the database, you could see how many hours that person has done that day. So columns from 1 to how many days there are in the month.

Right now I get a row for each day, with the correct sum of time worked on just one column, as there's one row per column.

Here's a picture of what I'd like the table to look like:

A picture of the table with columns for each day of the month

Answer 1

There is a solution for this using conditional aggregation... that will requires you to write 31 CASE statements, like :

SELECT 
    e.name, 
    SUM(CASE WHEN DAYOFMONTH(t.input_date) = 1 THEN t.time_worked ELSE 0 END) AS day1,
    SUM(CASE WHEN DAYOFMONTH(t.input_date) = 2 THEN t.time_worked ELSE 0 END) AS day2,
    SUM(CASE WHEN DAYOFMONTH(t.input_date) = 3 THEN t.time_worked ELSE 0 END) AS day3,
    ...
FROM 
    t_transactions t
    LEFT JOIN t_email e ON t.email_id = e.email_id 
WHERE YEAR(input_date) = 2019 AND MONTH(t.input_date) = 2
GROUP BY e.name
ORDER BY e.name

Other remarks :

• I guess that you meant t.email_id = e.email_id instead of t.email_id >= e.email_id

• it will probably more efficient to use MySQL built-in date functions such as YEAR , DAYOFMONTH and MONTH , which return integers, rather than manipulating formated string representations of dates

• as not all of the fields in your query were aliase, I made the assumption that columns input_date and time_worked belong to table t_transactions .

• since we SELECT e.name , this column needs to appear in the GROUP BY clause ; on non-ancient versions of MySQL, this is a syntax error