A database is a place to store data.
A relational database system (RDMS) stores data in tables.
Each table has rows and columns, much like a spreadsheet.
Each row has one or more columns to store data values.
SQL stands for Structured Query Language.
SQL is a language used to retrieve and manipulate data in a RDMS.
In a relational database data is stored in tables.
As an example, the table below has data in 4 rows and 3 columns.
A relational database contains tables which store data that is related in some way. SQL is the language that allows retrieval and manipulation of table data in a relational database.
The database below has 2 tables: one with data on Users and another with data on Products. SQL is the language with which you retrieve data, update data, and remove data.
This tutorial uses a database which is a modernized version of Microsoft's Northwind database. Northwind is a fictitious store that sells specialty food products from all over the world. The database has 5 tables with information on Products, Suppliers, Customers, and Orders.
Below is an Entity Relationship Diagram (ERD) which shows the tables and their relationships.