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Education

This is the Education section of the Command Prompt Website. Here you will find blogs specifically about how to use Postgres and related technologies.

How to Concatenate Strings in PostgreSQL

In PostgreSQL, the “||” operator and a built-in function named “CONCAT()” are used to concatenate multiple strings, characters, etc.

How to Use RETURNING Clause in PostgreSQL

In Postgres, the “RETURNING” clause is used with the INSERT, DELETE or UPDATE queries to retrieve the newly inserted, deleted, or updated data.

How to Show Databases in PostgreSQL

In PostgreSQL, the “\l” statement and “pg_databases” catalog are used to show the list of databases. Use the “\l+” command to show databases with more details.

PostgreSQL Primary Key - A Complete Guide

To create a primary key in Postgres, the user must specify the “PRIMARY KEY” keyword along with the name of the targeted column.

How Do I Count Unique Values in PostgreSQL?

In PostgreSQL, the DISTINCT clause can be used with the COUNT() function to count only unique/distinct values of a table.

PostgreSQL Foreign Key With Practical Examples

Foreign keys allows us to link the data of one table to others. The table referencing the foreign key is known as child table, while the table referenced by the foreign key is known as parent table.

How to Use EXCEPT Operator in PostgreSQL?

In PostgreSQL, EXCEPT returns the rows that exist in the result set of the first SELECT query but not in the result set of the second SELECT query.

How to Use Check Constraint in PostgreSQL?

CHECK constraints in PostgreSQL allow us to specify Boolean conditions for inserting or updating values in one or more columns.

PostgreSQL SERIAL- How to Create Auto-increment Columns

PostgreSQL offers a Pseudo-type known as SERIAL. It allows Postgres users to create auto-incremented columns in a table. Using SERIAL, you can create a sequence of integers.

PostgreSQL NOT NULL Constraint With Examples

The NOT NULL constraint ensures that the column accepts only non-null values. In Postgres, the CHECK constraint can be used as an alternative to the NOT NULL.