COLUMNS

Provides table column information. For columns of Iceberg external tables, see ICEBERG_COLUMNS.

Examples

=> SELECT table_schema, table_name, column_name, data_type, is_nullable
   FROM columns WHERE table_schema = 'store'
   AND data_type = 'Date';
 table_schema |    table_name     |      column_name       | data_type | is_nullable
--------------+-------------------+------------------------+-----------+-------------
 store        | store_dimension   | first_open_date        | Date      | f
 store        | store_dimension   | last_remodel_date      | Date      | f
 store        | store_orders_fact | date_ordered           | Date      | f
 store        | store_orders_fact | date_shipped           | Date      | f
 store        | store_orders_fact | expected_delivery_date | Date      | f
 store        | store_orders_fact | date_delivered         | Date      | f
6 rows)

In the following query, datetime_precision is NULL because the table definition declares no precision:

=> CREATE TABLE c (c TIMESTAMP);
CREATE TABLE
=> SELECT table_name, column_name, datetime_precision FROM columns
   WHERE table_name = 'c';
 table_name | column_name | datetime_precision
------------+-------------+--------------------
 c          | c           |
(1 row)

In the following example, timestamp precision is set:

=> DROP TABLE c;
=> CREATE TABLE c (c TIMESTAMP(4));
CREATE TABLE
=> SELECT table_name, column_name, datetime_precision FROM columns
   WHERE table_name = 'c';
 table_name | column_name | datetime_precision
------------+-------------+--------------------
 c          | c           |                  4

An IDENTITY column sequence is defined in a table's DDL. Column values automatically increment as new rows are added. The following query returns identity columns:

=> CREATE TABLE employees (employeeID IDENTITY, fname varchar(36), lname varchar(36));
CREATE TABLE
=> SELECT table_name, column_name, is_identity FROM columns WHERE is_identity = 't';
 table_name | column_name | is_identity
------------+-------------+-------------
 employees  | employeeID  | t
(1 row)

You can query the SEQUENCES table to get detailed information about an IDENTITY column sequence:

=> SELECT sequence_schema, sequence_name, identity_table_name, sequence_id FROM sequences WHERE identity_table_name ='employees';
 sequence_schema |      sequence_name       | identity_table_name |    sequence_id
-----------------+--------------------------+---------------------+-------------------
 public          | employees_employeeID_seq | employees           | 45035996273848816
(1 row)

For details about sequences and IDENTITY columns, see Sequences.