Introduction PostgreSQL is one of the most widely used database management systems. One of the easiest ways to use PostgreSQL on macOS is the Postgres.app. Postgres.app provides a simple interface for setting up a server and a command-line interface (psql) for interacting with databases via the terminal. In...
Introduction In this tutorial, we want to calculcate the sum of values of a specific column. In order to do this, we use the SUM function. We have already created the table student with the following data: Example 1 We want to calculcate the sum of credit points of all...
Introduction In this tutorial, we want to count the number of unique values of a specific column. In order to do this, we use the COUNT function with the DISTINCT keyword. We have already created the table student with the following data: Example 1 We want to count the number...
Introduction In this tutorial, we want to count the number of values of a specific column. In order to do this, we use the COUNT function. We have already created the table student with the following data: Example 1 We want to count the total number of students. In order...
Introduction In this tutorial, we want to select data from a table that satisfy a certain condition. In order to do this, we use the SELECT Statement with the WHERE Clause. We have already created the table student with the following data: Example 1 We want to select all columns...
Introduction In this tutorial, we want to select data from a table and sort the result set. In order to do this, we use the SELECT Statement with the ORDER BY Clause. We have already created the table student with the following data: Example 1 - Sort rows in ascending...
Introduction In this tutorial, we want to select a specific number of rows from a table by using a SQL Statement. In order to do this, we use the SELECT Statement with the LIMIT Clause. We have already created the table student with the following data: SQL Statement We want...
Introduction In this tutorial, we want to select data from a table by using a SQL Statement. The result should not contain duplicate rows. In order to do this, we use the SELECT Statement with the DISTINCT Clause. We have already created the table student with the following data: Example...
Introduction In this tutorial, we want to select data from a table by using a SQL Statement. In order to do this, we use the SELECT Statement. We have already created the table student with the following data: Example 1 - SELECT specific columns We want to select the columns...