将 Pivot 与子查询一起使用时，列定义不明确

Question

I am trying to run this pivot query to show the dates as columns which are in this format: "MM/DD/YYYY" and the occurrences of some kind of ID's in each date:

The column which contains the dates is "DATE_POSTED" -- DATA TYPE date The column which contains the ID's is "ID_INST" -- DATA TYPE varchar2

Query:

SELECT *
FROM (SELECT ID_INST, DATE_POSTED
      FROM total.table1) PIVOT XML (COUNT (DATE_POSTED)
                                           FOR (DATE_POSTED)
                                           IN  (SELECT distinct DATE_POSTED
                                                  FROM total.table1));

The error which i'm receiving is ORA-00918: column ambiguously defined, I did some searches but I keep getting this error. Not sure if my approach is totally correct. PS im using XML keyword due to the fact that it prompted: missing keyword

Current table:

Expected result:

Answer 1

Try the following:

SELECT *
  FROM (SELECT ID_INST, TO_CHAR(DATE_POSTED, 'DD-Mon')  DATE_POSTED
          FROM TOTAL.TABLE1)
  PIVOT XML (COUNT(DATE_POSTED)
             FOR DATE_POSTED IN (ANY))

The poblem might be caused by the fact, that date also stores time information additional to the date.

So you get different values for DATE_POSTED , but the conversion to char leads to the same column name as the date format mask cuts the time information.