合并表中的行

Question

My table consists of availability status data for each day of the month where a row represents a given month and each column is a day. I stores statuses like 'Available', 'Unavailable', etc.

This works great until I want to display data by week. The issue I run into is when I get to a week that crosses into the next month. Right now I'm using a query that looks like:

$query = "SELECT pilots.id AS pid, "
       . "pilots.last_name AS last_name, "
       . "pilots.first_name AS first_name, "
       . "rt.* FROM pilots "
       . "LEFT JOIN ("
       . "SELECT * FROM availability "
       . "WHERE date ='"  
       . $first_date_of_month->format("Y-m-d") 
       . $next_month_str . "')rt "
       . "ON pilots.id = rt.pilot_id "
       . "ORDER BY pilots.last_name, pilots.first_name, pid";

Which looks like:

SELECT p.id pid
     , p.last_name
     , p.first_name
     , rt.* 
  FROM pilots p
  LEFT 
  JOIN 
     ( SELECT * 
         FROM availability 
        WHERE date ='2017-06-01' 
         OR date = '2017-07-01'
     )rt 
    ON p.id = rt.pilot_id 
 ORDER 
    BY p.last_name
     , p.first_name
     , pid

The problem with this is let's say I have 1 user and 2 months of data. It returns 2 rows. I really only want 1 row where the data is merged using columns from the end of one month and beginning of another month.

For example:

//Pilots
-------------------------
| id|first_name|last_name|
-------------------------
| 1 | "myTest" |"myTest" |
-------------------------

// Months
----------------------------------------------------------------------
| id|pilot_id|  date  |   1_status  |   2_status  |....|  30_status  |
|--------------------------------------------------------------------|
| 1 |   1    |3/1/2017| "Available" |"Unavailable"|....| "Available" |
|--------------------------------------------------------------------|
| 2 |   1    |4/1/2017|"Unavailable"|"Unavailable"|....|"Unavailable"|
----------------------------------------------------------------------

In the first example (not within 7 days of the end of the month), it's simple: I will have 1 record because I know I do not need the next month. Let's say it's "3/21/2017"; I just output the statuses for "3/21/2017", "3/22/2017", and so on.

However, let's say the week I want to display starts at "3/28/2017". I need the data from March and for April. In this case, it generates 2 rows of data for pilot_id 1. But I really only need 28_status, 29_status, 30_status, 31_status, and THEN need 1_status, 2_status (all from April).

Attached $next_month_str below:

            $next_month_str = "";
            if (!is_last_day_of_month($sunday_date))
            {
                $next_month = get_next_month($monday_date);
                $next_month_str = "' OR date = '";
                $next_month_str = $next_month_str . $next_month->format("Y-m-d");
                $next_month_str = $next_month_str;
            }

$query_inner = "SELECT pilot_id, 26_status, 27_status, 28_status, 29_status, 30_status FROM availability WHERE date = '2017-06-01'";
$query = "SELECT availability.pilot_id AS pid, rt.26_status, rt.27_status, rt.28_status, rt.29_status, rt.30_status, availability.1_status, availability.2_status FROM availability INNER JOIN (" . $query_inner . ")rt ON rt.pilot_id = pid WHERE date = '2017-07-01'";

There are two queries I came up with. Separate they work fine, and they work fine when I test them out using a SQL checker and they do exactly what I want. However, when I run it in my site, they give me a error querying the database.

Answer 1

Based on your question, you need to use GROUP BY , HAVING and possibly GROUP_CONCAT() to essentially "flatten" your results set. Here are some resources so you may learn how and then apply that knowledge.

• GROUP_CONCAT()
• GROUP BY, HAVING

The above resources have a sandbox for you try play around with the SQL statements.

Answer 2

Solved it.

I can build the query string programatically, but using JOINs I was able to solve it. Does exactly what I want it to. Here is an example of a string:

SELECT availability.pilot_id, rt.26_status, rt.27_status, rt.28_status, rt.29_status, rt.30_status, availability.1_status, availability.2_status FROM availability INNER JOIN (SELECT pilot_id, 26_status, 27_status, 28_status, 29_status, 30_status FROM availability WHERE date = '2017-06-01')rt ON rt.pilot_id = availability.pilot_id WHERE date = '2017-07-01'

EDIT: Although I was able to solve the question using this, ultimately it was a design issue that forced this. I decided to refactor and use a table like availability {id, pilot_id, date, status}.