ERROR 1049 (42000): Unknown Database

Error Message#

ERROR 1049 (42000): Unknown database 'database_name'

Description#

This error occurs when you attempt to connect to or use a MySQL database that doesn't exist on the server. MySQL can't find the specified database name in its system catalogs.

Causes#

• Typos in the database name (remember MySQL is case-sensitive on some systems)
• The database hasn't been created yet
• The database existed previously but was deleted
• Using incorrect case on case-sensitive file systems
• Attempting to access a database on the wrong MySQL instance
• Special characters in database names not properly encoded
• The user may not have SHOW DATABASES privilege to see the database

Solutions#

1. Verify available databases:

   -- List all databases you have access to
   SHOW DATABASES;
   
   -- Check databases inside a Docker container
   docker exec -it mysql_container mysql -u root -p -e "SHOW DATABASES;"

2. Create the database if it doesn't exist:

   -- Create the database
   CREATE DATABASE database_name;
   
   -- Or with specific character set and collation
   CREATE DATABASE database_name
   CHARACTER SET utf8mb4
   COLLATE utf8mb4_unicode_ci;
   
   -- Create only if it doesn't exist (MySQL 5.7+)
   CREATE DATABASE IF NOT EXISTS database_name;

3. Check connection settings:

   -- Connect with explicit database name
   mysql -u username -p -h hostname database_name

4. Check user privileges:

   -- View privileges for the current user
   SHOW GRANTS;
   
   -- Grant privileges for the database to the user
   GRANT ALL PRIVILEGES ON database_name.* TO 'username'@'hostname';
   FLUSH PRIVILEGES;

Prevention#

1. Use standard naming conventions for databases:

   • Avoid special characters
   • Consider using lowercase names to avoid case sensitivity issues
   • Document database names

2. Create databases with IF NOT EXISTS:

   CREATE DATABASE IF NOT EXISTS database_name;

3. Check database existence in application code before attempting connections

4. Implement database creation in deployment scripts or migrations