Experts in Postgres and Open Source Infrastructure

PostgreSQL allows us to concatenate a string with a number using a built-in “CONCAT()” function or a pipe concatenation operator “||”.

A Postgres user's attributes can be changed using the ALTER USER statement. Using the ALTER USER command, we can modify/alter the user's password, privileges, etc..

To find the logged-in users in Postgres, the “pg_stat_activity” view is used. While to find all Postgres users, a system table named "pg_user" is used.

Postgres offers various built-in length functions to calculate the length of a string, such as LENGTH(), BIT_LENGTH(), CHAR_LENGTH(), and BYTE_LENGTH().

In PostgreSQL, the ALTER USER and ALTER ROLE statements are used along with the SUPERUSER attribute to change an ordinary user to a superuser.

In PostgreSQL, Users must execute the DROP CONSTRAINT with the ALTER TABLE command to drop any particular constraint from a Postgres table.

PostgreSQL doesn’t support the NVL() function. In Postgres, a built-in function named COALESCE() is used as an alternative to the NVL() function.

To rename a particular table in PostgreSQL, use the RENAME TO clause in conjunction with the ALTER TABLE statement.

To create a superuser in PostgreSQL, users must use the CREATE ROLE or CREATE USER statement along with the SUPERUSER attribute.

In PostgreSQL, there is no SYSDATE function. However, PostgreSQL provides different functions that are equivalent to the SYSDATE function.