The following list contains the four different items when working with a SQL database.

1. databases,
2. tables,
3. rows, and
4. columns.

These are the terms for the different elements of the database. You might think of these as containers, each containing information that is more specific. In a way, they are like stackable measuring cups, each fitting inside the next larger container.
When you are querying the database, you need to include information in your request that indicates where to find the data to query. That information includes the database and other items that contain the data.