Global Temporary Tables - unable to insert rows

I've never seen the syntax you are using. You are using "CREATE GLOBAL TEMPORARY TABLE .. AS SELECT ... FROM table"

First, 'table' is a reserved word, so you won't be able to do that anyway.

Seconly, you create the temp table once only.

Each session uses it with inserts, updates, deletes, etc. and data is deleted at end of transaction or at end of session, depending on your options. You sayd "ON COMMIT PRESERVE ROWS" so this will last until the session ends.

Have you tried this?

CREATE GLOBAL TEMPORARY TABLE tmp_inventory 
(
  COLUMN1          NUMBER                  NOT NULL,
  COLUMN2          NUMBER                  NOT NULL,
  COLUMN3          VARCHAR2(4000 BYTE)
)
ON COMMIT PRESERVE ROWS
;
 
-- After this is created once, what happens when you try to INSERT some data, then SELECT the data back?

                                              

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I have to correct part of my response, never having created TEMP tables using the " AS SELECT ... FROM" I see from researching that it is legal, but I'm unclear on the semantics, so I have something to learn here myself.

You still cannot use the keyword 'table' as you did, as it is a reserved word, but my answer is not complete.

I just created one myself in that style, but after disconnecting my session and reconnecting, the table was not there. Maybe another Oracle expert can shed some light. I've always pre-created a temporary table with an empty structure, never pre-populated.

After testing this again, I must have made a typo the first time around.

I created the table as select * from another table, disconnected, then logged in and the table was there, but empty again, so I am back to my original statement, I do not see the reason to combine the explicit table definition
      
CREATE GLOBAL TEMPORARY TABLE tmp_inventory
(
  COLUMN1          NUMBER                  NOT NULL,
  COLUMN2          NUMBER                  NOT NULL,
  COLUMN3          VARCHAR2(4000 BYTE)
)
ON COMMIT PRESERVE ROWS

With an "AS SELECT * FROM OTHER_TABLE"

I apologize if thinking out loud confused you, please let me know. Your original SQL was still invalid syntax, as TABLE is a reserved word.

I'm happy to not use the AS SELECT syntax.
Here's my results:

Create table works fine
INSERT INTO ... VALUES works fine, the rows show up

BUT

INSERT INTO tmp_inventory SELECT COLUMN1,  COLUMN2, COLUMN3  FROM some_table

Runs without errors but no rows are put in the table.

After doing:

INSERT INTO tmp_inventory SELECT COLUMN1,  COLUMN2, COLUMN3  FROM some_table

Runs without errors but no rows are put in the table.

Are you issuing COMMIT as well? Or are you trying to select data from other session? How you have created global temporary table? Using "ON COMMIT PRESERVE ROWS" or "ON COMMIT DELETE ROWS"?