[SPARK-28796][DOC]Document DROP DATABASE statement in SQL Reference

docs/sql-ref-syntax-ddl-drop-database.md

@@ -19,4 +19,62 @@ license: |
   limitations under the License.
 ---
 
-**This page is under construction**
+### Description
+
+Drop a database and delete the directory associated with the database from the file system. An 
+exception will be thrown if the database does not exist in the system. 
+
+### Syntax
+
+{% highlight sql %}
+DROP (DATABASE|SCHEMA) [IF EXISTS] dbname [RESTRICT|CASCADE];
+{% endhighlight %}
+
+
+### Parameters
+
+<dl>
+  <dt><code><em>DATABASE|SCHEMA</em></code></dt>
+  <dd>`DATABASE` and `SCHEMA` mean the same thing, either of them can be used.</dd>
+</dl>
+
+<dl>
+  <dt><code><em>IF EXISTS</em></code></dt>
+  <dd>If specified, no exception is thrown when the database does not exist.</dd>
+</dl>
+
+<dl>
+  <dt><code><em>RESTRICT</em></code></dt>
+  <dd>If specified, will restrict dropping a non-empty database and is enabled by default.</dd>
+</dl>
+
+<dl>
+  <dt><code><em>CASCADE</em></code></dt>
+  <dd>If specified, will drop all the associated tables and functions.</dd>
+</dl>
+
+### Example
+{% highlight sql %}
+-- Create `inventory_db` Database
+CREATE DATABASE inventory_db COMMENT 'This database is used to maintain Inventory';
+
+-- Drop the database and it's tables
+DROP DATABASE inventory_db CASCADE;
++---------+
+| Result  |
++---------+
++---------+
+
+-- Drop the database using IF EXISTS
+DROP DATABASE IF EXISTS inventory_db CASCADE;
++---------+
+| Result  |
++---------+
++---------+
+
+{% endhighlight %}
+
+### Related statements
+- [CREATE DATABASE](sql-ref-syntax-ddl-create-database.html)
+- [DESCRIBE DATABASE](sql-ref-syntax-aux-describe-database.html)
+- [SHOW DATABASES](sql-ref-syntax-aux-show-databases.html)