Oracle PL/SQL/System Tables Views/DBA TAB COLUMNS

Query column_name, hidden_column, data_type from DBA_TAB_COLS for a table name

 
SQL> create or replace type Job as object (
  2   firstname varchar2(30),
  3   surname varchar2(30),
  4   date_of_birth date,
  5   end_date date,
  6   item_count number(4),
  7   items_retrieved varchar2(1)
  8  )
  9  /
Type created.
SQL> create table Task (
  2   person_id number(10),
  3   job_detail Job
  4  );
Table created.
SQL>
SQL> set long 50000
SQL> select text from dba_views where view_name = "DBA_TAB_COLUMNS"
  2  /
TEXT
--------------------------------------------------------------------------------
select OWNER, TABLE_NAME,
       COLUMN_NAME, DATA_TYPE, DATA_TYPE_MOD, DATA_TYPE_OWNER,
       DATA_LENGTH, DATA_PRECISION, DATA_SCALE, NULLABLE, COLUMN_ID,
       DEFAULT_LENGTH, DATA_DEFAULT, NUM_DISTINCT, LOW_VALUE, HIGH_VALUE,
       DENSITY, NUM_NULLS, NUM_BUCKETS, LAST_ANALYZED, SAMPLE_SIZE,
       CHARACTER_SET_NAME, CHAR_COL_DECL_LENGTH,
       GLOBAL_STATS, USER_STATS, AVG_COL_LEN, CHAR_LENGTH, CHAR_USED,
       V80_FMT_IMAGE, DATA_UPGRADED, HISTOGRAM
  from DBA_TAB_COLS
 where HIDDEN_COLUMN = "NO"

1 row selected.
SQL> select column_name, hidden_column, data_type from DBA_TAB_COLS where table_name = "TASK"
  2  /

SQL> drop table Task;
Table dropped.
SQL>

Using the DBA_TAB_COLUMNS View

  
SQL>
SQL> --
SQL>
SQL> select column_name,data_type, nullable from dba_tab_columns
  2  where rownum < 50;
COLUMN_NAME
------------------------------
DATA_TYPE
--------------------------------------------------
N
-
SPARE6
DATE
Y
SPARE5
VARCHAR2
Y
SPARE4
VARCHAR2
Y
SPARE3
NUMBER
Y
SPARE2
NUMBER
Y
SPARE1
NUMBER
Y
INTCOL#
NUMBER
N
OFFSET
NUMBER
N
SEGCOLLENGTH
NUMBER

COLUMN_NAME
------------------------------
DATA_TYPE
--------------------------------------------------
N
-
N
SEGCOL#
NUMBER
N
POS#
NUMBER
N
COL#
NUMBER
N
BO#
NUMBER
N
OBJ#
NUMBER
N
SPARE6
DATE
Y
SPARE5
VARCHAR2
Y
SPARE4
VARCHAR2
Y
SPARE3
NUMBER
Y
SPARE2
NUMBER
Y
SPARE1
NUMBER
Y
CON#
NUMBER
N
NAME
VARCHAR2
N
OWNER#
NUMBER
N
SPARE6
DATE
Y
SPARE5
VARCHAR2
Y
SPARE4
VARCHAR2
Y
SPARE3
NUMBER
Y
SPARE2
NUMBER
Y
SPARE1
NUMBER
Y
FLAGS
NUMBER
Y
OPTIMAL
NUMBER
Y
KEEP
NUMBER
Y
UGRP#
NUMBER
Y
TS#
NUMBER
Y
STATUS$
NUMBER
N
INST#
NUMBER
Y
UNDOSQN
NUMBER
Y
XACTSQN
NUMBER
Y
SCNWRP
NUMBER
Y
SCNBAS
NUMBER
Y
BLOCK#
NUMBER
N
FILE#
NUMBER
N
USER#
NUMBER
N
NAME
VARCHAR2
N
US#
NUMBER
N
OBJ#
NUMBER
Y
ROLE#
NUMBER
N
PROXY#
NUMBER
N
CLIENT#
NUMBER
N

49 rows selected.