Select datatype of the field in postgres

postgresql

How do I get datatype of specific field from table in postgres ? For example I have the following table, student_details ( stu_id integer, stu_name varchar(30 ), joined_date timestamp );

In this using the field name / or any other way, I need to get the datatype of the specific field. Is there any possibility ?

Solution 1:

You can get data types from the information_schema (8.4 docs referenced here, but this is not a new feature):

=# select column_name, data_type from information_schema.columns
-# where table_name = 'config';
    column_name     | data_type 
--------------------+-----------
 id                 | integer
 default_printer_id | integer
 master_host_enable | boolean
(3 rows)

Solution 2:

You can use the pg_typeof() function, which also works well for arbitrary values.

SELECT pg_typeof("stu_id"), pg_typeof(100) from student_details limit 1;

Solution 3:

Try this request :

SELECT column_name, data_type FROM information_schema.columns WHERE 
table_name = 'YOUR_TABLE' AND column_name = 'YOUR_FIELD';

Solution 4:

run psql -E and then \d student_details

Solution 5:

If you like 'Mike Sherrill' solution but don't want to use psql, I used this query to get the missing information:

select column_name,
case 
    when domain_name is not null then domain_name
    when data_type='character varying' THEN 'varchar('||character_maximum_length||')'
    when data_type='numeric' THEN 'numeric('||numeric_precision||','||numeric_scale||')'
    else data_type
end as myType
from information_schema.columns
where table_name='test'

with result:

column_name |     myType
-------------+-------------------
 test_id     | test_domain
 test_vc     | varchar(15)
 test_n      | numeric(15,3)
 big_n       | bigint
 ip_addr     | inet