Oracle 11g Release 2

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CREATE TABLE T_00_RQMM (ID NUMBER(18,0))
INSERT INTO T_00_RQMM
VALUES(NULL)
1 rows affected

INSERT INTO T_00_RQMM
VALUES(100)
1 rows affected

CREATE TABLE t1 AS
SELECT MAX(ID) ID FROM T_00_RQMM
1 rows affected

CREATE TABLE t2 AS SELECT ID FROM( SELECT ID FROM T_00_RQMM ORDER BY ID DESC ) WHERE ROWNUM =1; 
1 rows affected

CREATE TABLE t3 AS
SELECT CAST(MAX(ID) AS NUMBER(18,0)) ID FROM T_00_RQMM
1 rows affected

SELECT TABLE_NAME, COLUMN_NAME, DATA_PRECISION, DATA_SCALE
FROM all_tab_cols
where table_name in ('T1', 'T2', 'T3')
ORDER BY Table_name


TABLE_NAME
COLUMN_NAME
DATA_PRECISION
DATA_SCALE


T1
ID
null
null

T2
ID
18
0

T3
ID
18
0