我正在组合一个查询，该查询在很多场合通过别名引用一个表，但它会进入状态：
* ORA-00904：“MPAN_STATUS”。“MPANCORE”：标识符无效
00904. 00000 - “％s：无效标识符”
*原因：
动作：
行错误：43列：126
查询如下：
SELECT readings.mpancore, mtds.meterid, (SELECT CASE
WHEN meter_type
LIKE 'RCAM%' AND
retrieval_method = 'R'
THEN 'TRUE'
ELSE 'FALSE' END
FROM edmgr.mtds
WHERE meter_removed IS NULL) "IS_SMART",
(SELECT CASE
WHEN flowversion = 'D0010' AND
readings.filename IS NOT NULL AND
readings.filedate >= mpan_status.ssd
THEN 'TRUE'
ELSE 'FALSE' END
FROM edmgr.readings, edmgr.mpan_status
WHERE readings.mpancore = mpan_status.mpancore) "D0010_RECEIVED",
(SELECT CASE
WHEN effective_from_date >= mpan_status.ssd AND
dc_id = mpan_status.confirmed_dc_id
THEN 'TRUE'
ELSE 'FALSE' END
FROM edmgr.D0019_reg, edmgr.mpan_status) "D0019_RECEIVED",
(SELECT CASE
WHEN file_date_time <= SYSDATE-409
THEN 'TRUE'
ELSE 'FALSE' END
FROM edmgr.D0019_reg) "RF_READ",
(SELECT CASE
WHEN file_date_time <= SYSDATE-220
THEN 'TRUE'
ELSE 'FALSE' END
FROM edmgr.D0019_reg) "R3_READ",
(SELECT CASE
WHEN file_date_time <= SYSDATE-118
THEN 'TRUE'
ELSE 'FALSE' END
FROM edmgr.D0019_reg) "R2_READ",
(SELECT CASE
WHEN file_date_time <= SYSDATE-56
THEN 'TRUE'
ELSE 'FALSE' END
FROM edmgr.D0019_reg) "R1_READ"
FROM edmgr.mpan_status "mpan_status" LEFT JOIN edmgr.D0019_reg "D0019" ON mpan_status.mpancore = D0019.metering_system_id
LEFT JOIN edmgr.readings "readings" ON mpan_status.mpancore = readings.mpancore
LEFT JOIN edmgr.mtds "mtds" ON readings.mpancore = mtds.mpancore
AND D0019.metering_system_id = mtds.mpancore
AND mtds.meterid = readings.meterid
我真的是一个完整的新手，所以非常感谢任何帮助。
答案 0 :(得分：0)
让我们开始定义ORA-00904 error：
ORA-00904字符串：无效的标识符 原因：输入的列名称丢失或无效。
操作：输入有效的列名称。有效列名必须以字母开头，小于或等于30个字符，并且仅包含字母数字字符和特殊字符$，_和＃。
如果它包含其他字符，则必须用双引号括起来。它可能不是一个保留字。
这也是一个区分大小写的问题（在FROM参数中将mpan_status放在引号中。）在Oracle中，只有当您将它们放在引号中时，列名称才区分大小写。
编辑：
这是一个建议我会编写查询（避免使用ANSI连接和子查询）。
SELECT readings.mpancore,
mtds.meterid,
CASE
WHEN meter_type LIKE 'RCAM%' AND retrieval_method = 'R' THEN 'TRUE'
ELSE 'FALSE'
END AS "IS_SMART"
FROM edmgr.mpan_status,
edmgr.mtds,
edmgr.D0019_reg,
edmgr.readings
WHERE mpan_status.mpancore = D0019_reg.metering_system_id
AND mpan_status.mpancore = readings.mpancore
AND readings.mpancore = mtds.mpancore
AND D0019_reg.metering_system_id = mtds.mpancore;