Postgres and Open Source Experts

In PostgreSQL, the INTERSECT operator combines the result set of at least two queries. The INTERSECT operator retrieves only common records from the targeted tables.

Importing CSV files into Postgres tables or exporting tables from PostgreSQL into CSV files are very common. In PostgreSQL, you can import a CSV file to a table using the \COPY statement(CLI) or pgAdmin(GUI).

In this write-up, we will learn various ways to import a CSV file to a Postgres table. So, let’s begin.

How to Use the \COPY Command in PostgreSQL?

You can use the \COPY statement to import …

In PostgreSQL, there are multiple ways to export a table into a CSV file, such as the COPY statement or the \COPY command.

PostgreSQL provides a built-in function named UNNEST() that accepts an array as an argument and expands the given array into a set of rows.

Sometimes we have to store the unique records in a table, such as an email address, employee id, etc. To achieve this purpose, the “UNIQUE” constraint is used in PostgreSQL. The UNIQUE constraint allows us to store the unique rows/records in a table.

This post will explain the working of the UNIQUE constraint through practical examples. So, let’s begin.

How Does UNIQUE Constraint Work in PostgreSQL?

Each time when you …

PostgreSQL offers a CAST operator that takes an expression and a data type and converts the given expression into the specified data type.

The DROP command throws an error if a table to be dropped doesn’t exist while “DROP IF EXISTS” shows a notice instead of throwing an error.

In Postgres, the SELECT DISTINCT clause fetches only unique values from a result set returned by a query. It retains only one row from a set of duplicated rows.

In PostgreSQL, the COALESCE() function handles the null values more efficiently. It accepts unlimited arguments and returns the first non-null argument.

PostgreSQL doesn’t provide a DATEADD function to add an interval to date time. However, you can achieve the same functionality using the “+” and “-” operators.