简单地说，这不是Oracle。
我注解了部分代码，这些代码肯定不会工作，

• 无效的日期格式掩码（有关有效选项，请参阅文档）
• 串联运算符是双管道，而不是加号
• 没有datediff函数
• %60也是错误的;我不知道它在你使用的语言中是什么
• Oracle中的空字符串等于NULL

我尽我所能去解决它，我理解。

SELECT attendanceid,
         e.firstname || ' ' || e.lastname AS fullname,
         e.empid,
         e.jobcode,
         e.address AS location,
         e.vsms_id,
         a.loginid,
         UPPER (shiftname) shiftname,
         --
         TO_CHAR (attendancedate, 'dd-mon-yy') attendancedate,
         -- TO_CHAR (attendancedate, 'dd-MMM-yy') attendancedate,
         --
         TO_CHAR (attendancedate, 'ddd') AS dayname1,
         --
         TO_CHAR (shiftstarttime, 'hh:mi') shiftstarttime,
         -- TO_CHAR (ShiftStartTime, 'hh:mm tt') ShiftStartTime,
         --
         TO_CHAR (shiftendtime, 'hh:mi') shiftendtime,
         -- TO_CHAR (ShiftEndTime, 'hh:mm tt') ShiftEndTime,
         /*
         TO_CHAR((SignOut,SignIn)/60 )|| ' Hrs' || ':' || SUBSTR('0' || TO_CHAR( (SignOut,SignIn)%60)(2)),
         GREATEST(-LENGTH('0' + TO_CHAR(DATEDIFF(SignOutMinute -SignIn, SignOut)%60 AS VARCHAR2(2))), -2))||' Min' as Duration,
         */
         signin,
         signout,
         Remark
    FROM t_attendance_attendance a
         LEFT JOIN usermaster u ON u.loginid = a.loginid
         LEFT JOIN employeemaster e ON e.empid = u.empid
   WHERE     EXTRACT (YEAR FROM attendancedate) = v_year
         AND EXTRACT (MONTH FROM attendancedate) = v_month
         AND a.active = 1
         AND a.loginid = NVL (v_loginid, a.loginid)
             -- CASE WHEN NVL (v_loginid, '') = '' THEN a.loginid ELSE v_loginid END
ORDER BY a.attendancedate ASC;

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您的日期格式模型错误：MMM应该是MON，hh:mm tt应该是HH24:MI或HH12:MI AM，如果您想要日期名称，则ddd应该是day（或fmday）。
您还需要修复持续时间代码，因为DATEDIFF应该只是减法，而Oracle有MOD函数（而不是%运算符）;但是，您可以使用EXTRACT简化该问题：

SELECT AttendanceId,
       E.FIRSTNAME || ' ' || E.LASTNAME AS FullName,
       E.EmpID,
       E.JobCode,
       E.Address as Location,
       E.VSMS_Id,
       A.LoginId,
       upper(ShiftName) AS ShiftName,
       To_char(AttendanceDate, 'dd-mon-yy') AS AttendanceDate, 
       to_char(AttendanceDate, 'day') AS dayName1,  
       TO_CHAR(ShiftStartTime,'hh24:mi') AS ShiftStartTime, 
       TO_CHAR(ShiftEndTime,'hh24:mi') AS ShiftEndTime,
       EXTRACT(HOUR FROM (signout - signin) DAY TO SECOND) || ' Hrs'
       || ':'
       || LPAD(EXTRACT(MINUTE FROM (signout - signin) DAY TO SECOND), 2, '0') ||' Min'
         as Duration,
       SignIn,
       SignOut,
       Remark
FROM   T_ATTENDANCE_ATTENDANCE A  
       LEFT JOIN USERMASTER U
       ON U.LOGINID = A.LOGINID  
       LEFT JOIN EMPLOYEEMASTER E
       ON E.EMPID = U.EMPID    
WHERE  ATTENDANCEDATE >= TO_DATE(V_YEAR||'-'||V_MONTH||'-01', 'YYYY-MM-DD')
AND    ATTENDANCEDATE <  TO_DATE((V_YEAR+1)||'-'||V_MONTH||'-01', 'YYYY-MM-DD')
AND    A.active = 1  
And    (a.LoginId = V_LoginId OR v_loginid IS NULL) 
order by A.AttendanceDate ASC

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