Postgres and Open Source Experts

The SUM() is used to perform the addition on a set of values. Use the DISTINCT option with the SUM() function to calculate the sum of distinct values.

The table rows can be counted using PostgreSQL's COUNT() function. It is an aggregate function that enables us to count the rows that meet the specified condition. There are multiple ways to use the COUNT() function, such as COUNT(*), COUNT(col_name), and COUNT(DISTINCT col_name). Each implementation of the COUNT() function serves a different functionality.

Let’s learn the working of the COUNT() function through Practical examples.

How to Use COUNT(*) Function in …

In PostgreSQL, to get the substring’s location in a string, the POSITION() function is used. It returns an integer that represents the substring’s location.

In PostgreSQL, the NOT IN operator filters the query results and returns all the values of a result set except the specified values.

To get the top n rows of a table, the LIMIT clause is used in PostgreSQL. It assists us in getting the subset of rows generated by a query.

In PostgreSQL, the SMALLINT is used to store small integer values. It takes 2 bytes of storage and can store integers between -32,768 to +32,768.

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.