[SPARK-30575][DOC] Document HAVING Clause of SELECT statement in SQL Reference

docs/sql-ref-syntax-qry-select-having.md

@@ -18,5 +18,102 @@ license: |
   See the License for the specific language governing permissions and
   limitations under the License.
 ---
+The <code>HAVING</code> clause is used to filter the results produced by
+<code>GROUP BY</code> based on the specified condition. It is often used
+in the conjunction with a [GROUP BY](sql-ref-syntax-qry-select-groupby.html)
+clause.
 
-**This page is under construction**
+### Syntax
+{% highlight sql %}
+HAVING boolean_expression
+{% endhighlight %}
+
+### Parameters
+<dl>
+  <dt><code><em>boolean_expression</em></code></dt>
+  <dd>
+    Specifies any expression that evaluates to a result type <code>boolean</code>. Two or
+    more expressions may be combined together using the logical 
+    operators ( <code>AND</code>, <code>OR</code> ).<br><br>
+
+    <b>Note</b><br>
+    The expressions specified in the <code>HAVING</code> clause can only refer to:
+     <ol>
+      <li>Constants</li>
+      <li>Expressions that appear in GROUP BY</li>
+      <li>Aggregate functions</li>
+    </ol>
+  </dd>
+</dl>
+
+### Examples
+{% highlight sql %}
+CREATE TABLE dealer (id INT, city STRING, car_model STRING, quantity INT);
+INSERT INTO dealer  VALUES (100, 'Fremont', 'Honda Civic', 10),
+                          (100, 'Fremont', 'Honda Accord', 15),
+                          (100, 'Fremont', 'Honda CRV', 7),
+                          (200, 'Dublin', 'Honda Civic', 20),
+                          (200, 'Dublin', 'Honda Accord', 10),
+                          (200, 'Dublin', 'Honda CRV', 3),
+                          (300, 'San Jose', 'Honda Civic', 5),
+                          (300, 'San Jose', 'Honda Accord', 8);
+
+-- `HAVING` clause referring to column in `GROUP BY`.
+SELECT city, sum(quantity) AS sum FROM dealer GROUP BY city HAVING city = 'Fremont';
+
+  +-------+---+
+  |city   |sum|
+  +-------+---+
+  |Fremont|32 |
+  +-------+---+
+
+-- `HAVING` clause referring to aggregate function.
+SELECT city, sum(quantity) AS sum FROM dealer GROUP BY city HAVING sum(quantity) > 15;
+
+  +-------+---+
+  |   city|sum|
+  +-------+---+
+  | Dublin| 33|
+  |Fremont| 32|
+  +-------+---+
+
+-- `HAVING` clause referring to aggregate function by its alias.
+SELECT city, sum(quantity) AS sum FROM dealer GROUP BY city HAVING sum > 15;
+
+  +-------+---+
+  |   city|sum|
+  +-------+---+
+  | Dublin| 33|
+  |Fremont| 32|
+  +-------+---+
+
+-- `HAVING` clause referring to a different aggregate function than what is present in
+-- `SELECT` list.
+SELECT city, sum(quantity) AS sum FROM dealer GROUP BY city HAVING max(quantity) > 15;
+
+  +------+---+
+  |city  |sum|
+  +------+---+
+  |Dublin|33 |
+  +------+---+
+
+-- `HAVING` clause referring to constant expression.
+SELECT city, sum(quantity) AS sum FROM dealer GROUP BY city HAVING 1 > 0 ORDER BY city;
+
+  +--------+---+
+  |    city|sum|
+  +--------+---+
+  |  Dublin| 33|
+  | Fremont| 32|
+  |San Jose| 13|
+  +--------+---+
+
+-- `HAVING` clause without a `GROUP BY` clause.
+SELECT sum(quantity) AS sum FROM dealer HAVING sum(quantity) > 10;
+  +---+
+  |sum|
+  +---+
+  | 78|
+  +---+
+
+{% endhighlight %}