+ /**
+ * Field configuration
+ * Keys:
+ * - date - array of columns with dates and their event title,
+ * e.g. 'c_birthday' => 'Birthday'
+ * - name - array of name columns
+ * - nameFormat - sprintf-compatible name formatting instruction,
+ * uses name columns
+ *
+ * @var array
+ */
+ protected $fields;
+
+ /**
+ * Set SQL server configuration
+ *
+ * @param array $config SQL server configuration with keys:
+ * dsn, user, password, table and fields
+ */