双SQL查询 - JOIN

Question

I need a double SELECT sql query from 2 different tables with names visits & items 1.: SELECT visitid, visitdate, visitreason FROM visits WHERE personid = 10 2.: SELECT itemid, itemname, itemtime FROM items WHERE itemvisitid= visitid I think I need to do a JOIN but don’t know exactly how.

Table examples:

Table: visits

visitid | personid | visitdate  | visitreason
1       | 10       | 05/07/2014 | no reason
2       | 10       | 06/07/2014 | some reason
3       | 12       | 06/07/2014 | no reason
4       | 10       | 12/07/2014 | some other reason

Table: items

itemid | personid | itemvisitid | itemname | itemtime
1      |   10     |  2          | box      | 23
2      |   10     |  2          | clock    | 70            
3      |   10     | null        | water    | 50
4      |   10     | null        | paper    | 40
5      |   12     | 3           | box      | 26    

What I have now is this:

$query = "SELECT visitid, visitdate, visitreason FROM visits WHERE personid = '10' ORDER BY visitdate DESC";

// 2nd select: "SELECT itemid, itemname, itemtime FROM items WHERE itemvisitid= visitid";

    $db->setQuery($query);
    $results = $db->query();
while($row = mysqli_fetch_array($results)){
    echo "<tr>
        <td>".$row['visitid'].", ".$row['visitdate']."</td>
        <td>".$row['visitreason']."</td>
        <td>".$row['itemid'].",".$row['itemname'].", ".$row['itemtime']."</td>
        </tr>";     
}

I need results to be something like this:

<tr>
    <td>1, 05/07/2014</td><td>no reason</td><td></td>
    <td>2, 06/07/2014</td><td>some reason</td><td>1, box, 23<br />2, clock, 70</td>
    <td>4, 12/07/2014</td><td>some other reason</td><td></td>
</tr>

Answer 1

I guess your might to use GROUP_CONCAT like this:

DEMO: http://sqlfiddle.com/#!2/9d4e22/15

SELECT visitid, DATE_FORMAT(visitdate,'%m/%d/%Y'), visitreason,
GROUP_CONCAT(itemid,itemname, itemtime)
FROM visits  left join items on visits.visitid = items.itemvisitid
WHERE visits.personid = 10 
GROUP BY  visitid, visitdate, visitreason

You might want to read this to know GROUP_CONCAT :
How to use GROUP_CONCAT in a CONCAT in MySQL

The document of GROUP_CONCAT() is here:
http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html#function_group-concat hope this helps.