我正在尝试在oracle apex中构建一个图表，但我得到了一个无法解析sql查询的问题。感谢您的帮助。
SELECT NULL LINK,
E.EquipmentDescription LABEL,
sum(EC.TIMECHECKEDIN - EC.TIMECHECKEDOUT) VALUE
From EQUIPMENT_CHECKOUT EC
join EQUIPMENT E on E.EQUIPMENTID = EC.EQUIPMENTID
group by E.EQUIPMENTDESCRIPTION