ORA-01758 and hidden columns

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Statement 1

CREATE TABLE aaa (ID NUMBER, i NUMBER)

Table created.

Statement 2

INSERT INTO aaa VALUES (1,1)

1 row(s) inserted.

Statement 4

select column_name,data_type,data_length from user_tab_cols where table_name='AAA'


COLUMN_NAME DATA_TYPE DATA_LENGTH
ID NUMBER 22
I NUMBER 22

2 rows selected.

COLUMN_NAME	DATA_TYPE	DATA_LENGTH
ID	NUMBER	22
I	NUMBER	22

Statement 5

ALTER TABLE aaa ADD (a CHAR(7) NOT NULL, b NUMBER)

ORA-01758: table must be empty to add mandatory (NOT NULL) column

Statement 6

select column_name,data_type,data_length from user_tab_cols where table_name='AAA'


COLUMN_NAME DATA_TYPE DATA_LENGTH
ID NUMBER 22
I NUMBER 22
SYS_C00003_17031708:40:16$ CHAR 7
SYS_C00004_17031708:40:16$ NUMBER 22

4 rows selected.

Additional Information