3 Ways! How to Restore SQL Database from bak File

What is a bak file? SQL Server backup files usually end with a .bak extension and these bak files contain either a full backup or a differential backup of the database. These bak files contain full or differential backups of the database. These bak files allow us to restore the database state to the state it was in at the time of the backup.

In the field of data management, SQL Server database can be recovered from .bak file in case of database data loss, hardware failure or logical error. This is essential for recovery of lost or corrupted data from SQL database. Therefore, in this article, we will provide you with details on three quick ways on how to restore SQL database from bak file.

Requirements to Recover SQL Database

First, make sure you have a functioning SQL Server instance whose version should be compatible with the version of SQL Server used to create the backup file.

In addition, before restoring the database, check if the target server has sufficient disk space to accommodate the restored database.

Finally, you need to have proper permissions on the target SQL Server instance in order to perform the database restore operation.

Method 1: Restore SQL Database from bak File via SSMS

The relationship between .bak file and SQL Server Management Studio (SSMS) is that .bak file is a backup format for SQL Server databases and SSMS is an integrated environment provided by Microsoft for managing SQL Server databases. Therefore, in a database recovery scenario, SSMS provides a graphical interface and wizard features to help users restore SQL database from bak file.

The following are the specific steps on how to restore SQL database from bak file through SSMS:

1. Start SQL Server Management Studio (SSMS): Open SQL Server Management Studio and connect to the target SQL Server instance.
2. Open the “Restore Database” Wizard: Right-click the “Restore” option in the “Database” directory, select “Database… ” Select “Database…”. You can also navigate to “Databases” through Object Explorer, then right-click on the blank area and select “Restore Database” as well.
3. Source Device: Under the “General” tab, select “Recover from Device”, and click the “…” button on the right to specify the location of the .bak file. You can add one or more backup files.
4. Select Backup Sets: In the “Select Backup Sets” page, the system will list all available backup sets in the .bak file. Choose the appropriate backup set according to your actual needs, usually the most recent one that contains the required data.
5. Set Recovery Options: In the Options page, you can specify the recovery mode (e.g. Simple Recovery, Full Recovery, etc.) and whether or not to overwrite the existing database (if there is a database with the same name). For partial recovery, you may also need to set the transaction log chain and recovery point.
6. Execute the Recovery Operation: After confirming that all settings are correct, click “OK” to start the database recovery process. This process may take some time, depending on the backup file size and server performance.
7. Verify the Recovery Result: After the database recovery is completed, check whether the recovery is successful by querying the data table or checking the database properties.

Method 2: Restore SQL Database Server from bak File Using T-SQL

A .bak file is the physical file format for SQL Server database backups, while T-SQL (Transact-SQL) is a programming language used to manage the structure and data of SQL Server databases, which includes commands to perform restore operations on the database.

By writing T-SQL statements, you can also implement the ability to restore SQL database from bak file. The specific steps for restoring a SQL database from a .bak file using T-SQL statements are as follows:

Step 1: Determine the backup set information. In practice, you need to know the physical path where the .bak file to be restored is located, the backup set number and other information. This can usually be obtained by querying a system table such as backup set in the msdb database.

Step 2: Create the RESTORE statement. Use the RESTORE DATABASE statement to perform the database recovery operation. The basic structure of this statement is as follows:

Step 3: Execute the T-SQL Statement. Execute the above T-SQL statement on the target SQL Server instance, either by using a new query window in SSMS or by programmatically calling a SQL Server stored procedure.

Step 4: Verify the restore result. After the restore is completed, check whether the database is in the expected state, including but not limited to: database integrity, data consistency, and integration with other services or applications.

Due to the flexibility provided by the T-SQL statement, more complex options can also be included, such as the restoration of read-only transaction log backups, the application of tail log backups, the change of database owner, and so on. Adapt the T-SQL statement to meet specific recovery needs. In addition, when using T-SQL directly for database recovery in production environments, it is important to exercise extreme caution and ensure that you have an adequate maintenance window and a detailed recovery plan.

Method 3: SQL Database Recovery from .bak File via Command Line

A .bak file is the backup file format for SQL database. And, SQL database recovery operations, including restoring a database can be from a .bak file. Here, we provide a new way to realize the SQL database recovery from .bak file. That’s it can be performed through command line tools provided by SQL such as sqlcmd or the SQL Server module in PowerShell.

The specific steps to restore SQL database from bak file using Command Line are as follows:

Step 1: Ensure that the sqlcmd utility is installed and configure. On Windows systems, make sure that the SQL Server client utility is installed and that the %PATH% environment variable contains the directory where sqlcmd is located. For other systems, refer to the installation guide for your platform.

Step 2: Prepare the RESTORE statement. A complete T-SQL RESTORE statement is also required, just as in SSMS, identifying information such as the backup set path, logical filename, and location of the new data and log files.

Step 3: Write the RESTORE statement to a script file. Since sqlcmd does not support the direct entry of complex multi-line commands, it is common to save the T-SQL statement to a text file (such as restore.sql).

Step 4: Execute the script via sqlcmd. Open a command prompt or terminal window and run the following command to execute the restore.sql script:

Note: 

• The -S parameter specifies the SQL Server instance address (e.g. localhost\SQLExpress or remote server address).
• The -U and -P parameters specify the username and password for logging in (or you can consider using Integrated Security Authentication).
• The -i parameter is followed by the name of the script file to be executed.

Step 5: Verify the results. After the restore is complete, you can return to SQL Server Management Studio (SSMS) or continue to use sqlcmd to check the status and integrity of the database.

Alternative: How to Recover SQL Database without Backups

Recovering SQL database without backup can rely on the unwritten data blocks on disk to rebuild the database as much as possible. Although Microsoft SQL Server itself does not provide data recovery in the absence of backups, some third-party specialized database recovery software does exist on the market claiming to handle this situation, such as MTM Database Recovery for SQL.

Below are the easy steps on how to use MTM Database Recovery for SQL tool to recover SQL database without backup:

Step 1: Select and download MTM Database Recovery for SQL software.

Step 2: After launching the software, click on “Recovery” to select the SQL Server instance from which you have damaged or lost data.

Step 3: Check the “Recover deleted data” and confirm the “Recover” button. The software will automatically detect and analyze the .mdf, .ldf files, or other related physical files associated with the damaged database and try to extract recoverable data from them.

Step 4: After the software completes scanning, the recoverable table structure and other data will be listed on the left side of the software. The right side is the detailed data preview area. According to the preview results, check the contents you want to recover.

Step 5: After confirming the content to be recovered, click the “Export” button and follow the instructions of the software to start the recovery process. The software will import the recovered SQL database into your specified database or export it to a CSV file.

Conclusion

With the above three approaches, even in the face of catastrophic data loss, we can effectively restore SQL database from bak file to safeguard business continuity and data integrity. Before performing database recovery, make sure you have enough downtime, as it may lead to service interruptions. In complex environments, you may also need to consider the synchronization of the database in terms of users, login information, and permissions.

Finally, we have also provided how to quickly restore SQL database data in the absence of a backup file. Hopefully, this article will help you solve the problem of corrupted SQL database efficiently.