Postgres and Open Source Experts

In Postgres, the DEFAULT keyword is used with the help of CREATE TABLE or ALTER TABLE statement to set a default value to a column.

To extract a year from a date, the built-in EXTRACT() and DATE_PART() functions are used in Postgres. To do so, pass the “YEAR" and the timestamp as arguments to any of these functions.

In PostgreSQL, the DELETE CASCADE feature allows us to delete the records associated with some other tables (via foreign key constraints).

In Postgres, the EXTRACT(), DATE_TRUNC(), and DATE_PART() functions are used to extract the month from a date field and then use the GROUP BY clause to group the results by month.

In PostgreSQL, the DATE_PART() function, INTERVAL, and the minus “-” operator is used to subtract a single or multiple days from a particular date.

The NOT operator is a frequently used operator in Postgres that negates a boolean expression. It allows us to filter or exclude certain data from the query’s result set.

In PostgreSQL, the NUMERIC data type is a more precise data type used to store decimal values. It can be defined with specific precision and scale.

Postgres allows you to find the list of active connections on your database server via the "pg_stat_activity" and pgAdmin's "Server Activity panel”.

In Postgres, the “\l”, “\list”, and “pg_catalog” are used to show the list of databases, while the “\dt” and “pg_catalog.pg_table” are used to show the list of relations.

Postgres offers a wide range of built-in functions to efficiently manipulate date and time values. For instance, NOW(), TO_TIMESTAMP(), CURRENT_DATE, etc.