updating SQL command for soft deleting datasets (#70)

Author: lmassaoy

api/src/main/java/marquez/db/DatasetDao.java

@@ -275,7 +275,9 @@ DatasetRow upsert(
   @SqlUpdate(
       """
         UPDATE datasets d
-        SET is_hidden = true
+        SET is_hidden = true,
+            is_deleted = true,
+            updated_at = CURRENT_TIMESTAMP
         FROM namespaces n
         WHERE n.uuid=d.namespace_uuid
         AND n.name=:namespaceName
@@ -285,7 +287,9 @@ DatasetRow upsert(
   @SqlQuery(
       """
         UPDATE datasets d
-        SET is_hidden = true
+        SET is_hidden = true,
+            is_deleted = true,
+            updated_at = CURRENT_TIMESTAMP
         FROM namespaces n
         WHERE n.uuid = d.namespace_uuid
         AND n.name=:namespaceName AND d.name=:name