Case Cast Number to Char Oracle SQL

Question

I am having an issue using case/cast properly to convert a number into a CHAR. I've look on stack overflow and keep seeing different techniques, but none seem to work for me. I am sure I am missing something simple, but this will be a good learning experience for me.

SELECT c.Client_ID,
   c.Last_Name,
   c.First_Name,
   d.Sched_Time,
   d.Time_In,
   d.Time_Out,
   (Round(d.Sched_Duration/15,1)) AS Units,
   (d.Time_Out - d.Time_In) * 60 * 24 AS Mins,
   CASE 
    WHEN d.Eventstatus = 1 THEN CAST('Completed' AS char(20))
    WHEN d.Eventstatus = 10 THEN CAST('Cancelled: No Show' AS char(20))
    WHEN d.Eventstatus = 11 THEN CAST('Cancelled: Early Dismissal' AS char(20))
    WHEN d.Eventstatus = 12 THEN CAST('Cancelled: Office Closed' AS char(20))
    WHEN d.Eventstatus = 13 THEN CAST('Deleted - Error' AS char(20))
    WHEN d.Eventstatus = 14 THEN CAST('Cancelled: Provider Absent' AS char(20))
    WHEN d.Eventstatus = 15 THEN CAST('Cancelled: Waiver' AS char(20))
    WHEN d.Eventstatus = 2 THEN CAST('Cancelled: Client Cancelled' AS char(20))
    WHEN d.Eventstatus = 3 THEN CAST('Pending Completion' AS char(20))
    WHEN d.Eventstatus = 4 THEN CAST('Cancelled: Absent' AS char(20))
    WHEN d.Eventstatus = 5 THEN CAST('Cancelled: Out Of Medication' AS char(20))
    WHEN d.Eventstatus = 6 THEN CAST('Cancelled: Other' AS char(20))
    WHEN d.Eventstatus = 7 THEN CAST('Cancelled: Field Trip' AS char(20))
    WHEN d.Eventstatus = 8 THEN CAST('Cancelled: Refused Treatment' AS char(20))
    ELSE d.Eventstatus
   END AS Appt_Status,
   CASE 
    WHEN d.Activity_Desc = '<b>OASAS</b>   <i>(Group)</i>' THEN 'OASAS -Group'
    WHEN d.Activity_Desc = '<b>OASAS</b>   <i>(Individual)</i>' THEN 'OASAS - Individual'
    ELSE d.Activity_Desc
   END AS Visit_Reason, 
   CASE 
    WHEN d.ProvidersID = 113706 THEN CAST('Name One' AS char(20)) 
    WHEN d.ProvidersID = 117917 THEN CAST('Name Two' AS char(20))
    WHEN d.ProvidersID = 117919 THEN CAST('Name Three' AS char(20))
    WHEN d.ProvidersID = 117920 THEN CAST('Name Four' AS char(20))
    WHEN d.ProvidersID = 117921 THEN CAST('Name Five' AS char(20))
    WHEN d.ProvidersID = 117922 THEN CAST('Name Six' AS char(20))
    ELSE d.ProvidersID
   END AS Provider,
   d.SRVID,
   d.dlsequence
   FROM Clients c
INNER JOIN DAILY_LOG_DATA d 
ON c.SHISID = d.SHISID
WHERE  d.SRVID IN (37913, 36186, 36185, 36180, 36179, 36168, 36167, 36182, 36181, 36173, 36172, 36177, 36176, 36175, 36174, 36178, 36184, 36183, 36188, 36187)
AND d.Sched_Time >= TO_DATE('2020-09-7 01:00:00', 'YYYY/MM/DD HH:MI:SS') 
AND d.Sched_Time  < TO_DATE('2020-09-16 12:59:00', 'YYYY/MM/DD HH:MI:SS')

Answer 1

Don't cast the literal strings to char() ; they are strings already, and doint so does not address the actual issue, which is that all branches of a case expression must return a value of the same datatype. Instead, cast the number to a string in the else branch of the case .

CASE 
    WHEN d.Eventstatus = 1 THEN 'Completed'
    WHEN d.Eventstatus = 10 THEN 'Cancelled: No Show'
    -- more "WHEN" branches here
    WHEN d.Eventstatus = 8 THEN 'Cancelled: Refused Treatment'
    ELSE TO_CHAR(d.Eventstatus)
END AS Appt_Status,

In Oracle, you could also use decode() :

DECODE(d.Eventstatus,
     1, 'Completed',
    10, 'Cancelled: No Show',
    -- ...
     8, 'Cancelled: Refused Treatment',
    TO_CHAR(d.Eventstatus)
 ) END AS Appt_Status