Let's say you have Postgres running in a pod on OpenShift. If you are not familiar with the oc command, refer to OpenShift - Getting Started with the oc command. The oc get pods command can be used to list the pods.

~]# oc get pods
NAME              READY   STATUS     RESTARTS  AGE
postgres-9mzm2    1/1     Running    0         8d

The oc exec and psql --list commands be used to list the Postgress databases.

~]# oc exec pod/postgres-9mzm2 -- psql --username postgres_user --list
                                 List of databases
   Name    |  Owner   | Encoding |  Collate   |   Ctype    |   Access privileges   
-----------+----------+----------+------------+------------+-----------------------
 db001     | postgres | UTF8     | en_US.utf8 | en_US.utf8 | 
 db002     | john.doe | UTF8     | en_US.utf8 | en_US.utf8 |

List the tables in a database.

~]# psql --username postgres_user --dbname my_database --command database_name "select * from pg_catalog.pg_tables"
     schemaname     |        tablename      | tableowner | tablespace | hasindexes | hasrules | hastriggers | rowsecurity 
--------------------+-----------------------+------------+------------+------------+----------+-------------+-------------
 public             | table001              | john.doe   |            | t          | f        | t           | f
 public             | table002              | john.doe   |            | t          | f        | f           | f
 public             | table003              | john.doe   |            | t          | f        | t           | f

And then you should be able to select the data from the columns in the table.

oc exec pod/postgres13-587bf9588f-xfcn2 -- psql --username postgres_user --dbname my_database --command "select * from your_table"