I wrote to you several times how to add a date.
It is necessary to realize that the SQL function for the date loads a local format that is not valid !!!
runSql("Update Specific Price", "UPDATE "._DB_PREFIX_."specific_price SET reduction = '0.180000', reduction_type = 'percentage' , `from` = '".date('Y-m-d H:i:s')."', `to` = '".date('Y-m-d H:i:s', strtotime(date('Y-m-d H:i:s').' +7 day'))."' WHERE id_specific_price = 18");