Oracle 12c - Ambiguous column in Insert Into Select Query, ORA-00918

Question

I am trying to execute multiple insert with single statement to achieve this I am using Insert into select statement. But I am facing when two columns have same value in insert. Error message that I am getting is ORA-00918: column ambiguously defined .

Query

INSERT INTO sample (
    HOST,
    TOTAL_PING,
    TOTAL_UNAVAILABLE_PING
)

SELECT * FROM (

    SELECT 'FR3158-73-1',
    82,
    82
    FROM DUAL
    UNION ALL

    SELECT 'FR3158-76-2',
    80,
    10
    FROM DUAL
)

Issue is there in first select statement where two values are 82 and 82, if I change one value to something works. I don't know how to make this work even if column values are same.

--- Updates ---

Table Definition

CREATE TABLE sample
(
  ID                      NUMBER GENERATED ALWAYS as IDENTITY(START with 1 INCREMENT by 1) PRIMARY KEY,
  HOST                    VARCHAR2(15 BYTE),
  TOTAL_PING              INTEGER,
  TOTAL_UNAVAILABLE_PING  INTEGER,
  ADDED_ON                TIMESTAMP(6)          DEFAULT systimestamp
);

Answer 1

In this case you don't need the subquery - as @Littlefoot showed. But if you did, with a more complicated scenario, you can avoid the error by aliasing the column expressions in the subquery:

INSERT INTO sample (
    HOST,
    TOTAL_PING,
    TOTAL_UNAVAILABLE_PING
)

SELECT * FROM (

    SELECT 'FR3158-73-1' as host,
    82 as total_ping,
    82 as total_unavailable_ping 
    FROM DUAL
    UNION ALL

    SELECT 'FR3158-76-2',
    80,
    10
    FROM DUAL
)
/

2 rows inserted.

---

The problem is that the subquery on its own gets implied column aliases, derived from the values in the first branch of the query:

SELECT 'FR3158-73-1',
82,
82 
FROM DUAL
UNION ALL

SELECT 'FR3158-76-2',
80,
10
FROM DUAL

'FR3158-73-         82         82
----------- ---------- ----------
FR3158-73-1         82         82
FR3158-76-2         80         10

The second and third columns are both called "82" , which is the ambiguity the ORA-00918 is complaining about, from the outer select . If you add aliases that goes away:

SELECT 'FR3158-73-1' as host,
82 as total_ping,
82 as total_unavailable_ping 
FROM DUAL
UNION ALL

SELECT 'FR3158-76-2',
80,
10
FROM DUAL

HOST        TOTAL_PING TOTAL_UNAVAILABLE_PING
----------- ---------- ----------------------
FR3158-73-1         82                     82
FR3158-76-2         80                     10

so the outer query is no longer confused. Note that you only need the aliases in the first branch of the union ( usually, anyway ) - it doesn't hurt to have them in all branches, they'll just be ignored, but it saves a bit of typing if you're creating this manually. The actual alias names also don't matter in this case, they just have to be unique; specifically, they don't have to match the columns you're inserting into - but it makes it easier to follow if they do.

If you do it as @Littlefoot showed you don't have the intermediate result set select , so the derived names don't need to be evaluated (if they can be said to exist at all), so the ambiguity is not seen - it's purely positional.

Answer 2

Remove select * from ( (and trailing ) ).

INSERT INTO sample (HOST, TOTAL_PING, TOTAL_UNAVAILABLE_PING)
   SELECT 'FR3158-73-1', 82, 82 FROM DUAL
           UNION ALL
           SELECT 'FR3158-76-2', 80, 10 FROM DUAL

---

[EDIT, after a comment that it still doesn't work]

Well, it works , at least in my 11gXE:

SQL> select * From v$version where rownum = 1;

BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Express Edition Release 11.2.0.2.0 - 64bit Production

SQL> CREATE TABLE sample
  2  (
  3    ID                      NUMBER,
  4    HOST                    VARCHAR2(15 BYTE),
  5    TOTAL_PING              INTEGER,
  6    TOTAL_UNAVAILABLE_PING  INTEGER,
  7    ADDED_ON                TIMESTAMP(6)          DEFAULT systimestamp
  8  );

Table created.

SQL> INSERT INTO sample (HOST, TOTAL_PING, TOTAL_UNAVAILABLE_PING)
  2     SELECT 'FR3158-73-1', 82, 82 FROM DUAL
  3             UNION ALL
  4             SELECT 'FR3158-76-2', 80, 10 FROM DUAL;

2 rows created.

No error on 12c either:

SQL> select * from v$version where rownum = 1;

BANNER                                                                               CON_ID
-------------------------------------------------------------------------------- ----------
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production              0

SQL> CREATE TABLE sample
  2  (
  3    ID                      NUMBER,
  4    HOST                    VARCHAR2(15 BYTE),
  5    TOTAL_PING              INTEGER,
  6    TOTAL_UNAVAILABLE_PING  INTEGER,
  7    ADDED_ON                TIMESTAMP(6)          DEFAULT systimestamp
  8  );

Table created.

SQL> INSERT INTO sample (HOST, TOTAL_PING, TOTAL_UNAVAILABLE_PING)
  2     SELECT 'FR3158-73-1', 82, 82 FROM DUAL
  3             UNION ALL
  4             SELECT 'FR3158-76-2', 80, 10 FROM DUAL;

2 rows created.

SQL>

Now, please, prove that it doesn't work on your database.

Answer 3

Try to name columns:

    INSERT INTO sample (HOST, TOTAL_PING, TOTAL_UNAVAILABLE_PING)
       SELECT 'FR3158-73-1' as host, 82 as total_ping, 82 as total_UNAVAILABLE_PING FROM DUAL
          UNION ALL
       SELECT 'FR3158-76-2' as host, 80 as total_ping, 10 as total_UNAVAILABLE_PING FROM DUAL
;

But better way is:

    INSERT INTO sample (HOST, TOTAL_PING, TOTAL_UNAVAILABLE_PING) values ('FR3158-73-1',82,82);
    INSERT INTO sample (HOST, TOTAL_PING, TOTAL_UNAVAILABLE_PING) values ('FR3158-76-2',80,10);

you avoid subquery. If you have lots of data to insert into the database consider SQL*Loader and loading from text file. https://docs.oracle.com/en/database/oracle/oracle-database/12.2/sutil/oracle-sql-loader-concepts.html#GUID-DD843EE2-1FAB-4E72-A115-21D97A501ECC