oracle 用户表、字段信息

1）dba_tab_columns/dba_tab_cols

SELECT *
FROM Dba_Tab_Cols
WHERE Table_Name = Upper('test_table_01');

SELECT *
FROM Dba_Tab_Columns
WHERE Table_Name = Upper('test_table_01');

查询这两个视图需要dba权限，dba_tab_columns基于dba_tab_cols，比如隐藏列，后者更全面：

create or replace view sys.dba_tab_columns as
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
from DBA_TAB_COLS
where HIDDEN_COLUMN = 'NO';

create or replace view sys.dba_tab_cols as
select u.name, o.name,
c.name,
decode(c.type#, 1, decode(c.charsetform, 2, 'NVARCHAR2', 'VARCHAR2'),
2, decode(c.scale, null,
decode(c.precision#, null, 'NUMBER', 'FLOAT'),
'NUMBER'),
8, 'LONG',
9, decode(c.charsetform, 2, 'NCHAR VARYING', 'VARCHAR'),
12, 'DATE', 23, 'RAW', 24, 'LONG RAW',
58, nvl2(ac.synobj#, (select o.name from obj$ o
where o.obj#=ac.synobj#), ot.name),
69, 'ROWID',
96, decode(c.charsetform, 2, 'NCHAR', 'CHAR'),
105, 'MLSLABEL',
106, 'MLSLABEL',
111, nvl2(ac.synobj#, (select o.name from obj$ o
where o.obj#=ac.synobj#), ot.name),
112, decode(c.charsetform, 2, 'NCLOB', 'CLOB'),
113, 'BLOB', 114, 'BFILE', 115, 'CFILE',
121, nvl2(ac.synobj#, (select o.name from obj$ o
where o.obj#=ac.synobj#), ot.name),
122, nvl2(ac.synobj#, (select o.name from obj$ o
where o.obj#=ac.synobj#), ot.name),
123, nvl2(ac.synobj#, (select o.name from obj$ o
where o.obj#=ac.synobj#), ot.name),
178, 'TIME(' ||c.scale|| ')',
179, 'TIME(' ||c.scale|| ')' || ' WITH TIME ZONE',
180, 'TIMESTAMP(' ||c.scale|| ')',
181, 'TIMESTAMP(' ||c.scale|| ')' || ' WITH TIME ZONE',
231, 'TIMESTAMP(' ||c.scale|| ')' || ' WITH LOCAL TIME ZONE',
182, 'INTERVAL YEAR(' ||c.precision#||') TO MONTH',
183, 'INTERVAL DAY(' ||c.precision#||') TO SECOND(' ||
c.scale || ')',
208, 'UROWID',
'UNDEFINED'),
decode(c.type#, 111, 'REF'),
nvl2(ac.synobj#, (select u.name from user$ u, obj$ o
where o.owner#=u.user# and o.obj#=ac.synobj#), ut.name),
c.length, c.precision#, c.scale,
decode(sign(c.null$),-1,'D', 0, 'Y', 'N'),
decode(c.col#, 0, to_number(null), c.col#), c.deflength,
c.default$, h.distcnt, h.lowval, h.hival, h.density, h.null_cnt,
decode(h.row_cnt, 0, 1, 1, 1, h.row_cnt-1), h.timestamp#, h.sample_size,
decode(c.charsetform, 1, 'CHAR_CS',
2, 'NCHAR_CS',
3, NLS_CHARSET_NAME(c.charsetid),
4, 'ARG:'||c.charsetid),
decode(c.charsetid, 0, to_number(NULL),
nls_charset_decl_len(c.length, c.charsetid)),
decode(bitand(h.spare2, 2), 2, 'YES', 'NO'),
decode(bitand(h.spare2, 1), 1, 'YES', 'NO'),
h.avgcln,
c.spare3,
decode(c.type#, 1, decode(bitand(c.property, 8388608), 0, 'B', 'C'),
96, decode(bitand(c.property, 8388608), 0, 'B', 'C'),
null),
decode(bitand(ac.flags, 128), 128, 'YES', 'NO'),
decode(o.status, 1, decode(bitand(ac.flags, 256), 256, 'NO', 'YES'),
decode(bitand(ac.flags, 2), 2, 'NO',
decode(bitand(ac.flags, 4), 4, 'NO',
decode(bitand(ac.flags, 8), 8, 'NO',
'N/A')))),
decode(c.property, 0, 'NO', decode(bitand(c.property, 32), 32, 'YES',
'NO')),
decode(c.property, 0, 'NO', decode(bitand(c.property, 8), 8, 'YES',
'NO')),
decode(c.segcol#, 0, to_number(null), c.segcol#), c.intcol#
from sys.col$ c, sys.obj$ o, sys.hist_head$ h, sys.user$ u,
sys.coltype$ ac, sys.obj$ ot, sys.user$ ut
where o.obj# = c.obj#
and o.owner# = u.user#
and c.obj# = h.obj#(+) and c.intcol# = h.intcol#(+)
and c.obj# = ac.obj#(+) and c.intcol# = ac.intcol#(+)
and ac.toid = ot.oid$(+)
and ot.type#(+) = 13
and ot.owner# = ut.user#(+)
and (o.type# in (3, 4)                                     /* cluster, view */
or
(o.type# = 2     /* tables, excluding iot - overflow and nested tables */
and
not exists (select null
from sys.tab$ t
where t.obj# = o.obj#
and (bitand(t.property, 512) = 512 or
bitand(t.property, 8192) = 8192))));

2）user_tab_columns/user_tab_cols

和dba视图类似，但只能查当前用户的表：

SELECT *
FROM User_Tab_Cols
WHERE Table_Name = Upper('test_table_01');

SELECT *
FROM User_Tab_Columns
WHERE Table_Name = Upper('test_table_01');

3）all_tab_columns/all_tab_cols

类似，这个能查询所有用户的表，不过个人感觉检索速度慢得多：

SELECT *
FROM All_Tab_Cols
WHERE Table_Name = Upper('test_table_01');

SELECT *
FROM All_Tab_Columns
WHERE Table_Name = Upper('test_table_01');

另：

xxx_tab_comments 可以查询表注释；

xxx_tab_statistics 可以查询列统计信息；

xxx_tab_privs 和 xxx_tab_privs_recd 可以查询该表授权信息；