Postgres and Open Source Experts

ALIASES are used in Postgres to provide a temporary name to the columns, tables, etc., while executing/writing Postgres queries.

In Postgres, the “column doesn’t exist” error occurs because of various reasons, such as the searched column doesn’t exist, typo mistakes, column alias being used incorrectly, etc.

To define an auto-incremented primary key in Postgres, specify a column name followed by a pseudo data type named “SERIAL”, and then specify the PRIMARY KEY keyword.

PostgreSQL offers an ARRAY_TO_STRING() function that accepts three arguments: an array, a delimiter, and a text to replace the null values.

The TRUNC() function trims the whole fractional part or up to specified precision, while the ROUND() function rounds the input number to the nearest integer/specified fractional places.

PostgreSQL allows us to create a string array using one of three data types: CHAR, VARCHAR, and TEXT. Once an array is created, various operations can be performed on that array.

ARRAY_REMOVE() function accepts an array and a specific number as arguments and deletes all the occurrences of that particular number from the input array.

In PostgreSQL, the UPDATE statement must be executed with the semi-colon-separated syntax to modify multiple rows with different values.

The ARRAY_REPLACE() is an inbuilt array function in Postgres that allows us to replace all the occurrences of an array element with a new element.

Pattern matching in PostgreSQL is performed using wildcards. PostgreSQL offers two wildcards represented with a percentage sign “%” and an underscore sign “_”.