Postgres and Open Source Experts

In Postgres, the EXISTS operator takes a subquery as an argument and checks the existence of a record in the subquery. Consequently, it returns true or false.

In Postgres, the ELSIF is one of the decision-driven statements that evaluate several conditions. It checks/evaluates each condition one by one.

In Postgres, the if statement checks a condition/criteria and returns true or false. If statement doesn’t handle the false condition. To handle the false conditions, the else statement is used in PostgreSQL.

In PostgreSQL, the upsert feature is used either to update existing records or insert new ones into a table. The upsert feature is implemented using the INSERT ON CONFLICT statement.

PostgreSQL allows us to copy an existing table with or without data. In Postgres, either you can copy only the structure of an existing table, or you can copy a table completely along with its data.

PostgreSQL provides a built-in function named SUBSTRING() that extracts a substring from any specific string. The SUBSTRING() function accepts three parameters: a string, starting position, and length. The starting position” and “length” parameters are optional that can be skipped depending on the situation.

This write-up will present a detailed overview of extracting a substring from a string using the PostgreSQL SUBSTRING() function. So, let's get started.

How to Use SUBSTRING() …

Installing the PostgreSQL on your machine will also install a couple of very handy tools, such as pgAdmin, and SQL SHELL. pgAdmin is a web-based GUI tool, while psql is a terminal-based tool. Both these tools assist us in working with Postgres.

This write-up will assist the beginners who have installed PostgreSQL on their PCs and are now looking to establish a connection to it. This post will cover the …

The AGE() function takes two timestamps as arguments, subtracts the second timestamp from the first one, and retrieves the resultant interval.

PostgreSQL provides a built-in function named TO_DATE() that assists us in converting a string into a date. The TO_DATE() function retrieves a date value in “YYYY-MM-DD” format.

In Postgres, the CURRENT_TIMESTAMP retrieves the date and time along with the time zone, while the LOCALTIMESTAMP function retrieves the date and time without the time zone.