Oracle使用列字段别名报错，报错信息提示为ORA-00923: FROM keyword not found where expected。SQL语句如下：

select bsourceec as 来源EC,

btriatradeflag as 三角贸易, 

casscustid as 客户,

castunitid as 单位, 

cbprojectid as 项目, 

cdevaddrid as 收货地点,

cdevareaid as 收货地区,

cecbillbid as 电子商务单据明细, 

cecbillid as 电子商务单据,

cectypecode as 电子商务单据类型,

cffileid as 特征码,

cpraybillrowno as 请购单行后,

cproductorid as 生产厂商,

cqpbaseschemeid as 优质优价方案, 

cqtunitid as 报价单位,

cqualitylevelid as 质量等级, 

crececountryid as 收货国家/地区, 

crowno as 行号,

csendcountryid as 发货国家/地区,

csrcbbid as 来源单据子表主键, 

csrcbid as 来源单据子表行主键, 

csrcid as 来源单据主表主键, 

ctaxcodeid as 税码, 

ctaxcountryid as 报税国家/地区, 

ctranspmodeid as 运输方式, 

cunitid as 主单位, 

delivdate as 计划收发货日期, 

fbuysellflag as 购销类型, 

ftaxtypeflag as 扣税类别,

nastnum as 数量, 

ncalcostmny as 计成本金额, 

ncaltaxmny as 计税金额, 

nglobalmny as  全局本币无税金额, 

nglobaltaxmny as 全局本币价税合计,

ngprice as 主本币无税单价, 

ngroupmny as 集团本币无税金额, 

ngrouptaxmny as 集团本币价税合计,

ngtaxprice as 主本币含税单价,

nmny as 本币无税金额,

nnosubtax as 不可抵扣税额, 

nnosubtaxrate as 不可抵扣税率,

nnum as 主数量,

nordnum as 累计订单主数量, 

nordsum, as 累计订单价税合计,

norigmny as 无税金额,

norigprice as 主无税单价, 

norigtax as 原币税额,

norigtaxmny as 价税合计, 

norigtaxprice as 主含税单价, 

noritotalgpmny as 累计合同应付核销金额, 

nqtorigprice as 报价无税单价,

nqtorigtaxprice as  报价含税单价, 

nqtprice,

nqttaxprice, 

nqtunitnum, 

nschedulernum, 

ntax as 税额, 

ntaxmny,

ntaxrate as 税率, 

ntotalgpmny, pk_arrvstock, 

pk_arrvstock_v as 收货库存组织, 

pk_arrvstoorg as 收货单位,

pk_arrvstoorg_v,

pk_ct_price,

pk_ct_pu,

pk_ct_pu_b,

pk_ctrelating as 关联合同表头主键, 

pk_ctrelating_b as 关联合同表体主键, pk_ecmct, pk_ecmct_b, 

pk_financeorg , 

pk_financeorg_v as 财务组织,  

pk_group as 集团, 

pk_marbasclass as 物料分类编码, 

pk_material as 物料编码, 

pk_org,

pk_org_v as 采购组织, 

pk_origctb as 原始合同基本主键, 

pk_praybill, pk_praybill_b, 

pk_receiveaddress as 收货地址,

pk_srcmaterial, ct_pu_b.ts, 

vbdef1, vbdef10, vbdef11, vbdef12, vbdef13, vbdef14, vbdef15, vbdef16, vbdef17, vbdef18, 

vbdef19, vbdef2, vbdef20, vbdef3, vbdef4, vbdef5, vbdef6, vbdef7, vbdef8, vbdef9, 

vchangerate, vctbillcode, vctbilltype, vecbillcode, vecmctbillcode, vfree1, vfree10, 

vfree2, vfree3, vfree4, vfree5, vfree6, vfree7, vfree8, vfree9, vmemo, 

vpraybillcode as 请购单号, 

vqtunitrate as 报价换算率,

vrstrantypecode as 来源单据交易类型, 

vsrccode as 来源单据号,

vsrcrowno as 来源单据行号, 

vsrctype  as 来源单据类型

from  ct_pu_b 

where ct_pu_b.pk_ct_pu = '1001A41000000005PZZX' and ct_pu_b.dr = 0