add exception if query is empty

Author: isublimity

src/Query/Query.php

@@ -30,6 +30,10 @@ class Query
      */
     public function __construct($sql,$degenerations=[])
     {
+        if (!trim($sql))
+        {
+            throw new QueryException('Empty Query');
+        }
         $this->sql = $sql;
         $this->degenerations=$degenerations;
     }

tests/ClientTest.php

@@ -613,6 +613,14 @@ public function testSqlConditions()
         );
     }
 
+
+    /**
+     * @expectedException \ClickHouseDB\QueryException
+     */
+    public function testWriteEmpty()
+    {
+        $this->db->write('');
+    }
     /**
      *
      */