SQL USE Database Statement

USE in SQL Syntax

Let's take a look at how the USE DATABASE statement is written in SQL:

In this case, the term DatabaseName refers to the specific name of the database we want to select.

The system makes sure that each database name is special and only used once within the relational database management system (RDBMS). This ensures that databases are uniquely identified and prevents naming conflicts within the system.

USE in SQL Example

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Basic Usage of the SQL USE DATABASE Statement

The basic usage of the SQL USE DATABASE statement involves designating a specific database for your actions. Before diving into a practical example, it's important to ensure that the database you intend to work with has been created using the CREATE DATABASE query.

For instance, consider a scenario where we want to manage employee information within a database. Let's start by creating a new database called EmployeeDB:

Once the database is created, we can use the USE command to select it:

By executing the above command, we switch our focus to the EmployeeDB database, enabling us to carry out operations exclusively within this database's context.

Before Using Any Database Using the Use Command, It’s Necessary to First Create It

First, we'll start by creating a new database using the SQL command:

After creating the database, we can see the list of all available databases like this:

The result will show the names of various databases and now, we'll use the following query to choose myDatabase as the one we want to work with:

Once we switch to the myDatabase, we can carry out different tasks. For example, let's create a new table named Employee:

Next, we'll insert some records into the Employee table using SQL INSERT statements:

To verify our operations, we can retrieve the records from the Employee table using the SQL SELECT statement:

The output will show the details of the employees:

USE DATABASE Statement on Non-Existing Database

If you try to choose a database that hasn't been created yet, you'll run into a problem. In this example, we're attempting to switch to a database with the name DatabaseName, but it hasn't been set up.

When you run the query above, you'll see a message like this:

Output:

This message indicates that the system doesn't recognize the name you provided because the database doesn't exist.

To resolve this, you need to create the database if it doesn't exist already and then re-run the USE Statement to switch to the newly created database.