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Subjects in the Big Room
2:13Which subject/s are taught in the largest room?
And also,
which subjects are taught in that room?
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For this query, we'll need to find a way
to tie together the subjects table, and
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the rooms table.
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And to do that,
we can use the classes table.
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The CLASSES table has both the SUBJECT_ID
column and a ROOM_ID column.
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So, let's start by
selecting everything from
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the classes table WHERE
the ROOM_ID is = to 19.
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Then from here,
we need to join to the subjects table, so
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we can resolve these subjects into
whatever subjects they actually are.
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So to do this, we're going to join from,
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CLASSES.SUBJECT_ID to SUBJECTS.ID.
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So back in the query, let's add a JOIN,
and let's join to SUBJECTS on
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CLASSES.SUBJECT_ID = SUBJECTS.ID.
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And if we run it now, We can see
the subjects table pulling in over here.
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So it looks like the two classes
taught in room 19 are band and choir.
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But how would we get this down to just
two rows that say band and choir?
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Well, for starters,
let's not select everything.
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Let's just select the NAME, and
since there's only one NAME column,
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this NAME is going to be
from the subjects table.
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And if we run this, we get band,
band, band and choir, choir, choir.
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And real quick,
why we're getting six rows for
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this, is just because there's
three classes of each one.
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One row for each class.
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So, getting back to our names here,
band, band, band, choir, choir, choir.
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If we wanna get these down to two rows,
we just need to use the distinct keyword,
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which will return one row for
each instance of a value and a column.
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And now if we run it,
we see that I spelled distinct wrong.
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So let's add a C.
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And then we get the coloring to let
us know this is actually a keyword.
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And we can run it, and
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we get band and choir as the subjects
that are taught in room 19.
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