Experts in Postgres and Open Source Infrastructure

VARCHAR(n) or CHARACTER VARYING(n) is a data type in PostgreSQL that stores textual data within a limited range. It can store n number of characters.

Execute the “\dt” command from psql tool or use the pg_catalog schema with the aid of the SELECT query from the pgAdmin to show tables of the selected database.

The EXTRACT() function in PostgreSQL extracts a specific field, like a day, month, minutes, hours, etc., from an INTERVAL or TIMESTAMP.

PostgreSQL offers a built-in function named SPLIT_PART() that splits the given string based on the specified delimiter. It returns the ‘n’ number of substrings.

In PostgreSQL, the CONCAT() function accepts multiple strings as arguments and concatenates them to a single string. Strings can be char, text, or varchar.

In PostgreSQL, the UNION clause/operator combines the result sets of two or more queries. It doesn’t return the duplicated rows in the combined set.

PostgreSQL provides a built-in function named the ROUND() function that accepts either one or two arguments/values. It rounds a number to the nearest integer.

Specify a string followed by “::” and then write the data type to convert the given string into the targeted type like integer, decimal, or double precision.

TO_NUMBER() is used to convert a character string to a number. The TO_NUMBER() function accepts two parameters, a “string” and a “format”.

In PostgreSQL, the BOOLEAN or BOOL data type takes only 1 byte to store a value in a database, and it returns one of two probable values: True or False.