MySQL SELECT子查询多对多关系

Question

I have a bilingual dictionary database that I've created, and the tables are set up like so:

lemma (lemmaID, lemma, meaning)

collocate (collocateID, lemmaID, collocate, notes, connection)

collusage (usageID, lemmaID_u, collocateID_u, japanese, english, englishalt)

partofspeech (posID, partofspeech)

postolemma (lemmaID_p, posID_p)

So far, I have a query that returns tables for the results, and it works just how I'd like it to. (It looks like this )

$q = 'SELECT *
FROM lemma, collocates, collusage
WHERE lemma.lemmaID = collocates.lemmaID AND lemma.lemmaID = collusage.lemmaID_u AND collusage.collocateID_u = collocates.collocateID
ORDER BY lemma.lemmaID;';

$result = mysqli_query($con, $q) or die(mysql_error());

if (!$result || mysqli_num_rows($result) == 0) {
    echo 'No rows found';
    exit;
}

$lastCatID = 0;

while ($row = mysqli_fetch_assoc($result)) {
    $reading = $row['reading'];
    $headword = $row['lemma'];

    $collocate = $row['collocate'];

    if (isset($row['notes'])) {
        $notes = '('.$row['notes'].')';
    } else {
        $notes = $row['notes'];
    }

    $japanese = $row['japanese'];
    $english = $row['english'];

    if (isset($row['englishalt'])) {
        $englishalt = ', '.$row['englishalt'].'';
    } else {
        $englishalt = $row['englishalt'];
    }

    if ($lastCatID != $row['lemmaID']) {
        //starting a new category
        if ($lastCatID != 0) {
            //close up previous table
            echo '    </tbody>
            </table> </div>';
        }
        //start a new div
                echo '<div class="entry">
                <h4>'.$reading.'【'.$headword.'】 <span class="pos">'.$WANT TO LIST PARTS OF SPEECH HERE.'</span></h4>
                <table class="table table-striped table-hover">

                    <tbody>';
        $lastCatID = $row['lemmaID'];
    }

    echo '<tr>
            <td><span>'.$collocate.'</span><span class="notes">'.$notes.'</span></td>
            <td>'.$japanese.'</td>
            <td>'.$english.''.$englishalt.'</td>
            </tr>';
}

        if ($lastCatID != 0) {
            //close up the final table
            echo '    </tbody>
            </table></div>';
        }

        mysqli_free_result($result);

What I can't figure out how to do is to use the postolemma junction table to get all of the partofspeech values for each lemmaID so I can list them next to the lemma in the table. Everything SELECT query I have done so far has duplicated collocation entries, which I don't want. Any help is appreciated!

Edit: Here is a link to the SQL Fiddle with data. I couldn't get my foreign key constraints to work so just that is missing.

Answer 1

if I understand you correctly you want to select all values from table partofspeech based on lemma table. Your query should look like this:

SELECT part.partofspeech 
FROM partofspeech part
INNER JOIN postolemma post
    ON part.posID = post.posID_p
INNER JOIN lemma l
    ON post.lemmaID_p = l.lemmaID

Also I would suggest you to change the query you use and start using JOIN operator in syntax, it's good practice and it's not hard to switch from one to another... So your query:

SELECT *
FROM lemma, collocates, collusage
WHERE lemma.lemmaID = collocates.lemmaID 
      AND lemma.lemmaID = collusage.lemmaID_u 
      AND collusage.collocateID_u = collocates.collocateID
ORDER BY lemma.lemmaID;

Will look like this:

 SELECT * 
 FROM lemma
 INNER JOIN collocates
     ON lemma.lemmaID = collocates.lemmaID
 INNER JOIN collusage
    ON collusage.collocateID_u = collocates.collocateID
    AND lemma.lemmaID = collusage.lemmaID_u
 ORDER BY lemma.lemmaID;

Also you can use aliases for table in you query like i do in first query I wrote here. It will make your life easier because you don't need to type whole name of table over and over...

GL!

PS also it's good to post your desired result in you question and provide SQL Fiddle with some data for our better understanding of your queston...

EDIT

After we consulted in the comments we come to this solution:

 SELECT * 
 FROM lemma
 INNER JOIN collocates
     ON lemma.lemmaID = collocates.lemmaID
 INNER JOIN collusage
    ON collusage.collocateID_u = collocates.collocateID
    AND lemma.lemmaID = collusage.lemmaID_u
 INNER JOIN (SELECT post.lemmaID_p AS lemmaID, group_concat(part.partofspeech SEPARATOR ', ') AS partofspeach
             FROM partofspeech part
             INNER JOIN postolemma post
               ON part.posID = post.posID_p
             INNER JOIN lemma l
               ON post.lemmaID_p = l.lemmaID
             GROUP BY post.lemmaID_p) tmp
 ON lemma.lemmaID = tmp.lemmaID
 ORDER BY lemma.lemmaID;

Here is SQL Fiddle for that...