slide tweaks
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@ -237,7 +237,7 @@
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SELECT tree_id FROM Trees WHERE spc_common = 'sycamore maple'
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</code></pre>
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<p style="font-size: 70%">Computes the <b>set-union</b> of any two <b>union-compatible</b> sets of tuples</p>
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<p style="font-size: 70%">Adding <code>ALL</code> preserves duplicates across the inputs.</p>
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<p style="font-size: 70%">Adding <code>ALL</code> preserves duplicates across the inputs (<b>bag-union</b>).</p>
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</section>
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<section>
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@ -247,15 +247,13 @@
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FROM relationlist
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WHERE condition
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GROUP BY groupinglist
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HAVING group-condition
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HAVING groupcondition
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</code></pre>
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<div style="font-size: 70%">
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<p>The target-list now contains...<ol class="tight" style="margin-top: 0px; margin-left: 100px;">
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<li>grouped attributes</li>
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<li>aggregate expressions</li>
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</ol></p>
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<p>Targets of type (1) must be a subset of the grouping-list</p>
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<p>The <span color="red">targetlist</span> now contains <b>(a)</b> Grouped attributes, and <b>(b)</b>Aggregate expressions.</p>
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<p>Targets of type (a) must be a subset of the grouping-list</p>
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<p style="font-size: 70%">(intuitively each answer tuple corresponds to a single group, and each group must have a single value for each attribute)</p>
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<p style="margin-top: 20px"><span color="red">groupcondition</span> is applied <i>after</i> aggregation and may contain aggregate expressions.</p>
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</div>
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</section>
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