Error
Error Code:
1046
MySQL Error 1046: No Database Selected
Description
Error 1046 indicates that your SQL query or operation requires a specific database context, but no database has been actively selected for use. This typically happens when you attempt to perform actions like querying tables without first telling MySQL which database to operate within.
Error Message
No database selected
Known Causes
3 known causesNo Database Selected for Session
You attempted to execute SQL statements (e.g., SELECT, INSERT) without explicitly issuing a `USE <database_name>;` command first in your current session.
Missing Database in Connection String
Your application or client tool connected to the MySQL server but did not specify a default database within its connection parameters or configuration.
Unqualified Table Names
You are referencing tables by name (e.g., `SELECT * FROM my_table;`) without qualifying them with a database name (e.g., `SELECT * FROM my_db.my_table;`) and no default database is selected.
Solutions
4 solutions available1. Select a Database Using the USE Statement easy
Explicitly tell MySQL which database to use for subsequent operations.
1
Connect to your MySQL server.
mysql -u your_username -p2
After connecting, use the `USE` statement followed by the name of your database.
USE your_database_name;3
You should see a confirmation message like 'Database changed'. Now you can execute your SQL commands.
SELECT * FROM your_table;2. Specify Database When Connecting easy
Provide the database name directly when initiating the MySQL client connection.
1
When you connect to the MySQL server using the command-line client, you can specify the default database directly.
mysql -u your_username -p your_database_name2
Enter your password when prompted. Once connected, the specified database will be automatically selected.
SELECT * FROM your_table;3. Specify Database in Connection String (Applications) medium
Ensure your application's database connection configuration includes the database name.
1
Locate your application's database connection configuration file or settings. This varies greatly depending on the programming language and framework you are using (e.g., `my.cnf`, `wp-config.php`, environment variables, connection strings in code).
Example (Python with SQLAlchemy):
engine = create_engine('mysql+mysqlconnector://user:password@host/your_database_name')2
Verify that the `database` or equivalent parameter in your connection string or configuration is correctly set to the name of the database you intend to use.
Example (PHP PDO):
$dsn = 'mysql:host=localhost;dbname=your_database_name';
$pdo = new PDO($dsn, $user, $password);3
Restart your application or re-establish the database connection after making any necessary changes to the configuration.
N/A4. Qualify Table Names with Database Name medium
Prefix table names with the database name for explicit referencing.
1
Instead of directly referencing a table, explicitly state the database name followed by a dot and then the table name.
SELECT * FROM your_database_name.your_table;2
This approach works even if no database is currently selected, as it fully qualifies the table's location.
INSERT INTO your_database_name.another_table (column1) VALUES ('some_value');