SQL server 2008 r2连接报错18456

Error 18456 in SQL Server 2008 R2 is a common error that occurs when there is a problem with the login credentials. Here are some steps you can try to resolve the issue: 1. Verify that the login credentials are correct. Make sure that the username and password are spelled correctly and that the account is not locked out or disabled. 2. Check if the SQL Server instance is configured to use Windows Authentication or SQL Server Authentication. If it is using SQL Server Authentication, make sure that the "SQL Server and Windows Authentication mode" option is enabled. 3. Ensure that the login has appropriate permissions to access the database. You can check this by running the following query: `SELECT * FROM sys.syslogins WHERE name = 'login_name'` 4. Check if the SQL Server instance is configured to use a default database for the login. If the default database is not available or the login does not have permission to access it, you may encounter error 18456. 5. Verify that the SQL Server instance is not configured to use an expired password policy. If none of these steps work, you may need to consult with a database administrator or IT professional for further assistance.