`USE` Statement in DBMS (MySQL) [ English ]

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Introduction

A database server can contain multiple databases. Before performing operations such as creating tables, inserting data, or retrieving records, a user must first select the database in which they want to work.

The USE statement is used to select a specific database and make it the current working database. Once a database is selected, all SQL operations will be performed within that database unless another database is selected.

Definition

The USE statement is used to select or switch to a particular database in the database server so that all subsequent SQL queries are executed in that database.

Syntax

USE database_name;

• database_name: The name of the database that you want to select.

How It Works

When the USE command is executed:

1. The DBMS checks whether the specified database exists.
2. If the database exists and the user has permission, it becomes the active database.
3. All subsequent commands such as CREATE TABLE, INSERT, SELECT, etc., will apply to that database.

Example

USE student_db;

After executing this command, student_db becomes the current database.

Now any table created will be stored inside this database.

Example:

CREATE TABLE students (
    id INT,
    name VARCHAR(50),
    course VARCHAR(50)
);

The students table will be created inside the student_db database.

Checking the Current Database

To check which database is currently selected, the following query can be used:

SELECT DATABASE();

Example Output:

This shows that student_db is the currently active database.

Important Notes

• The database must already exist before using the USE command.
• If the database does not exist, the DBMS will generate an error.
• The user must have permission to access the database.

Key Points

• USE is used to select a database for performing operations.
• Only one database can be active at a time in a session.
• After selecting a database, all tables and queries belong to that database.
• The command helps organize and manage database operations efficiently.

Summary

The USE statement is an important command in DBMS that allows users to select the database they want to work with. By setting a database as the current working database, users can easily perform operations such as creating tables, inserting data, and retrieving records within that specific database.