SQL

Many database designs separate information into different tables based on how certain data points relate to one another. Even in cases like this, it’s likely that there will be times when someone will want to retrieve information from more than one table at a time. A common way of accessing data from multiple tables in a single SQL operation is to combine the tables with a JOIN clause. This guide outlines how to retrieve data from multiple tables by joining them together.

When designing an SQL database, there may be cases where you want to impose restrictions on what data can be added to certain columns in a table. SQL makes this possible through the use of constraints. After applying a constraint to a column or table, any attempts to add…

When working with relational databases and Structured Query Language (SQL), you can store, manage, and retrieve data from the relational database management system. SQL can also perform calculations and manipulate data through the use of functions. In this tutorial, you’ll use different SQL functions to perform mathematical calculations, manipulate strings and dates, and calculate summaries using aggregate functions.