Alternate conditional insert syntax in DISPATCHER_CHECK_MEDIA_SERVER for MySQL

kamailio/dispatcher-role.cfg

@@ -221,7 +221,12 @@ route[DISPATCHER_CHECK_MEDIA_SERVER]
        if($var(Zone) != "MY_AMQP_ZONE") {
           $var(SetId) = 2;
        }
-       sql_query("exec", "insert into dispatcher (setid, destination) select $var(SetId), \"$var(MediaUrl)\" where not exists(select * from dispatcher where destination = \"$var(MediaUrl)\")");
+       if ("KAZOO_DB_URL" =~ "^mysql") {
+           sql_query("exec", "insert into dispatcher (setid, destination) select $var(SetId), \"$var(MediaUrl)\" from DUAL where not exists(select * from dispatcher where destination = \"$var(MediaUrl)\")");
+       }
+       else {
+           sql_query("exec", "insert into dispatcher (setid, destination) select $var(SetId), \"$var(MediaUrl)\" where not exists(select * from dispatcher where destination = \"$var(MediaUrl)\")");
+       }
        if($sqlrows(exec) > 0) {
           xlog("L_WARNING", "reloading dispatcher table\n");
           ds_reload();