Database Star

SQL Cross Apply and Outer Apply: The Complete Guide

Have you heard of the SQL Cross Apply feature but have no idea what it does? Or are you familiar with how both Cross Apply and Outer Apply work but don’t know how they can work in the real world?

Learn all about Cross Apply and Outer Apply in this guide, including:

What Cross Apply is
What Outer Apply is
How they differ from Inner and Outer Joins
Which databases support this feature
Why you would use it
Some realistic examples

Let’s get into the guide.

How to Show a List of Databases in SQL

If you want to see a list of databases on your server, you can run commands to do this. Let’s see how you can do this in several different SQL vendors.

SQL Drop Database Command

Sometimes you’ll need to delete a database or drop a database in SQL. There’s a command to do this in SQL. Let’s see how you can do this in different databases.

JSON in PostgreSQL: The Ultimate Guide

PostgreSQL has quite a lot of features for storing and working with JSON data.

In this guide, you’ll learn:

What JSON is and why you might want to use it
Creating a table to store JSON data
How to add, read, update, and delete JSON data
Tips for performance, validating and working with JSON

Let’s get into the guide.

SQL Show Tables: List All Tables in a Database

Do you need to get a list of all the tables in your SQL database?

Learn how to do this in several different database vendors in this guide.

How to Update from Select in SQL

The basic UPDATE statement in SQL allows us to update data in a table.

But what if we want to update data in one table based on data in another table?

There are a few ways to do that in different versions of SQL.

Let’s take a look at the SQL Update from Select techniques in this guide.

A Guide to DBMS_OUTPUT.PUT_LINE

In this guide, you’ll learn what the DBMS_OUTPUT.PUT_LINE function in Oracle does, see some examples, learn how to enable it in different editors, and learn why it should not be used in production code.

Let’s take a look.