Oracle column Datatype from metadata [duplicate] - oracle

Question

I want to get the columns names and datatype and its datatype's length .as example
if there is a table
SQL> create table TestTable(
2 ID VARCHAR2(4) NOT NULL,
3 CODE Number(5),
4 MyDate DATE,
5 MyNumber Number(8,2))
I need something like in some_column to identify separately number(5) is for an integer and number(8,2) is for a desimal value...
I tried this
SELECT column_name, data_type, data_length FROM USER_TAB_COLUMNS WHERE table_name = 'some_table'
but this data_length gives me the length in byte so I can't figure out when there is a case like number(5) ,number(8,2)..what I need is like somthing below
TABLE_NAME COLUMN_NAME DATA_TYPE some_column
------------------------------ ------------------------------ --------------------------
TESTTABLE ID VARCHAR2 4
TESTTABLE MYNAME VARCHAR2 5
TESTTABLE MYDATE DATE -
TESTTABLE MYNUMBER NUMBER 8,2
help?

Answer 1

There are data_precision and data_scale columns there.
Please take a look at this example:
create table qwer(
x number,
y number(8,2),
z number(5,0),
a int,
b decimal(5,3)
);
SELECT column_name, data_type, data_precision, data_scale
FROM USER_TAB_COLUMNS
WHERE Table_name = 'QWER'
;
COLUMN_NAME DATA_TYPE DATA_PRECISION DATA_SCALE
------------- --------- -------------- ----------
B NUMBER 5 3
A NUMBER
X NUMBER
Y NUMBER 8 2
Z NUMBER 5 0
EDIT
To find primary key columns you need to join two dictionary views, please see the below example:
CREATE TABLE pk1(
id int primary key,
name varchar2(10)
);
CREATE TABLE pk2(
id int ,
pk1 number(10,0),
pk2 varchar2(5),
name varchar2(10),
constraint my_composite_pk primary key (id, pk1, pk2 )
);
SELECT c.table_name, cols.column_name, cols.position
FROM user_constraints c
JOIN USER_CONS_COLUMNS cols
USING ( CONSTRAINT_NAME )
WHERE c.table_name IN ('PK1', 'PK2' )
and c.constraint_type = 'P' /* P - means PRIMARY KEY */
ORDER BY 1,3
;
TABLE_NAME COLUMN_NAME POSITION
---------- ----------- ----------
PK1 ID 1
PK2 ID 1
PK2 PK1 2
PK2 PK2 3

Answer 2

If this is only for Geetting information then just Press ALT+F1 on the name of the table this will show you the names of the columns with length and data types.

Answer 3

Why don't you try SELECT * FROM information_schema.columns ?
It has columns "table_schema, table_name, column_name, ordinal_position, is_nullable, data_type, character_maximum_length, character_octet_length, numeric_precision, numeric_scale, datetime_precision", etc.