Question

I’m putting together a query which references a table via an alias on numerous occasions, but it then proceeds to state:

*ORA-00904: “MPAN_STATUS”.”MPANCORE”: invalid identifier
00904. 00000 – “%s: invalid identifier”
*Cause:
Action:
Error at Line: 43 Column: 126

The query is as follows:

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

I’m a complete novice really, so any assistance would be greatly appreciated.

Answer 1

Let’s start off defining the ORA-00904 error:

ORA-00904 string: invalid identifier
Cause: The column name entered is either missing or invalid.

Action: Enter a valid column name. A valid column name must begin with a letter, be less than or equal to 30 characters, and consist of only alphanumeric characters and the special characters $, _, and #.

If it contains other characters, then it must be enclosed in double quotation marks. It may not be a reserved word.

Also it would be a case-sensitivity issue (where you put mpan_status in quotes, in the FROM argument.) In Oracle, column names are case-sensitive only when you put them in quotes.

EDIT:

Here’s a suggestion of I would write the query (avoiding the use of ANSI joins, and subqueries).

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;