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    <p>You're on the right track. I'd recommend looking at <a href="https://en.wikipedia.org/wiki/Join_%28SQL%29" rel="nofollow"><code>JOIN</code></a>s.</p> <p>I've provided a step-by-step answer on how to obtain the desired results. If you just want the final query, go down to step 5 and pick the one appropriate for your DBMS.</p> <h2>1: Selecting all comedy movie IDs:</h2> <pre><code>SELECT mvid FROM GenreInfo WHERE genre = 'Comedy'; </code></pre> <h2>2: Selecting the directorIDs of those movies</h2> <pre><code>SELECT directorID FROM DirectInfo JOIN GenreInfo ON DirectInfo.mvID = GenreInfo.mvID WHERE genre = 'Comedy'; </code></pre> <h2>3: Selecting the director name of those directors.</h2> <pre><code>SELECT firstname FROM DirectorInfo JOIN DirectInfo ON DirectorInfo.directorID = DirectInfo.directorID JOIN GenreInfo ON DirectInfo.mvID = GenreInfo.mvID WHERE genre = 'Comedy'; </code></pre> <h2>4: Grouping that query by director to get number of movies:</h2> <pre><code>SELECT firstname, COUNT(*) AS NumberOfMovies FROM DirectorInfo JOIN DirectInfo ON DirectorInfo.directorID = DirectInfo.directorID JOIN GenreInfo ON DirectInfo.mvID = GenreInfo.mvID WHERE genre = 'Comedy' GROUP BY DirectorInfo.directorID; </code></pre> <h2>5: Sort the results and get only the first one:</h2> <pre><code>SELECT firstname, COUNT(*) AS NumberOfMovies FROM DirectorInfo JOIN DirectInfo ON DirectorInfo.directorID = DirectInfo.directorID JOIN GenreInfo ON DirectInfo.mvID = GenreInfo.mvID WHERE genre = 'Comedy' GROUP BY DirectorInfo.directorID ORDER BY NumberOfMovies LIMIT 1; </code></pre> <p>If you're using SQL server, use <code>TOP</code> instead:</p> <pre><code>SELECT TOP 1 firstname, COUNT(*) AS NumberOfMovies FROM DirectorInfo JOIN DirectInfo ON DirectorInfo.directorID = DirectInfo.directorID JOIN GenreInfo ON DirectInfo.mvID = GenreInfo.mvID WHERE genre = 'Comedy' GROUP BY DirectorInfo.directorID ORDER BY NumberOfMovies; </code></pre>
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    1. POsql get a unique ID then count the number of tuples relating to that ID
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    1. CO+1 nicely explained :)
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    2. CO@rink Don't you think this might give an error because column in group by isn't included in select list.
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    3. COgood explanation, but if you provide the user with complete code of a homework, then you are not helping him get any knowledge :)
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