MS SQL Databases act as an integral part of numerous applications, powering businesses worldwide. In spite of their importance in keeping the data protected, their proper functioning is crucial. However, certain unwarranted circumstances may hamper the proper working of SQL databases, leaving the transaction log files (LDF) missing or corrupted. These damaged LDF files can pose a major threat to data integrity, and cause heavy data loss. 

The need is hence to rebuild SQL database with corrupt or deleted log files. Right here, we will discuss this topic in detail. Besides, we will also talk about Stellar Repair for MS SQL, an advanced third-party SQL database repair tool that deals withSQL database corruption with ease. The software ensures numerous other benefits for DBAs in ensuring flawless database functioning.

Rebuilding the database with corrupt or deleted log files

Before starting with the database rebuilding from a damaged log file, going through the SQL Server event and error logs will be wise. It will let you find hardware issues in the software that hosts the database.

These issues may act as the root cause behind the SQL database corruption. Fixing them may bring the database back to its usual state. If the problem persists, go on with the following suggestions.

Database restoration from a backup

A robust backup strategy is essential to keep your database running, come what may! Regular backups will help you to leverage the latest healthy image of the database in case of an unwanted event, like data loss or corruption. 

You may opt to have full, differential, or transaction log backups subject to your requirements. 

• A full backup will include data, schema information, and other details. 
• Differential backup will include the modifications carried out since the recent full backup. 
• Transaction log backup will enable point-in recovery by capturing all the database transactions since the previous full or differential backup. 

Combining these backup options will help actively in database restoration, thus saving it from SQL database corruption. Once you have a health backup, you can restore your database to the ‘last backup taken’.

Here are the steps for the same:

• Launch SQL Server Management Studio
• Navigate to  Object Explorer 
• Select and Right-click the database that you want to backup
• In the Restore Database window, provide the source of the backup location
• Select the database in the destination section to restore it to the last backup taken
• Under the Restore Plan, tick the backup file or choose a file if the window shows a list of backup files.
• Click OK to restore the database

Manual methods to rebuild SQL database

In the absence of a database backup, you can use several manual methods to rebuild the database with a deleted or corrupted log file. These methods are however risk-prone and require you to have a deep understanding of the ingrained SQL Server technicalities

1. Using the Repair Options

Using DBCC CHECKDB command with the REPAIR_ALLOW_DATA_LOSS option is a widely practiced method to rebuild the database. Here are the steps to do the same:

1. Set the database in emergency mode. For this, open Query Builder in SSMS and type this command: 

ALTER DATABASE [Your_DB_Name] SET EMERGENCY;

2. Next, set your database in Single Mode with the following command:

ALTER DATABASE [Your_DB_Name] SET SINGLE_USER;

3. Run DBCC CHECKDB command in combination with REPAIR_ALLOW_DATA_LOSS. The command below will repair the inconsistencies in the database. 

DBCC CHECKDB [Your_DB_Name] WITH REPAIR_ALLOW_DATA_LOSS;

Despite repairing the issues, this command can lead to data loss. So, consider it only during any unavoidable circumstance.

2. Recreating the log file

1. This method will work on offline databases. Hence, before starting, set the database to offline mode

ALTER DATABASE [Your_DB_Name] SET OFFLINE;

2. Find the corrupt LDF file and rename it. This will avert the accidental use of the file while rebuilding the SQL database.

3. Next, use the below T-SQL command to rebuild the file:

ALTER DATABASE [Your_DB_Name] REBUILD LOG ON (NAME = DBRecoverylogfile, FILENAME = ‘C:\Path\To\ DBRecoverylogfile.ldf’);

4. After rebuilding the log file, it is now time to bring the database back to online mode by typing the below command:

 ALTER DATABASE [Your_DB_Name] SET ONLINE;

Whether you use the REPAIR_ALLOW_DATA_LOSS command or recreate a file, both these manual methods are likely to accompany several issues. If the problem is severe, these solutions might not be enough.

Moreover, you would need to possess an in-depth knowledge of SQL Server and the associated T-SQL queries to remedy the situation. A comparably better, safer, and quicker method is to use an SQL database repair tool.

Using third-party SQL database repair tool

Many software are available to help you rebuild SQL database with corrupt or deleted log files. Using any such tool will set you free from facing the issues during the manual methods. Alongside, this method is a lot quicker and more accurate. 

A reputed tool to consider in this regard is Stellar Repair for MS SQL. Best to deal with SQL database corruption issues, it is the ultimate choice for Microsoft MVPs and IT professionals. Among its multiple features, include:

• Repairing Corrupt MDF and NDF files
• Repairing severely damaged large-sized databases
• Recovery of missing or deleted records from the database
• Support for SQL Server on Windows and Linux OS
• Facility to save multiple saves at the same time by using a parallel processing technique
• Recovery of SQL database objects like tables, triggers, rules, keys, indexes, and defaults
• Support for MS SQL Server 2022 and all the older versions

How it works?

Follow these easy steps to rebuild SQL database with corrupt or deleted log files:

• Choose the corrupt SQL database using the Browse or Search options
• Select the file and click the Repair button to repair the database
• Preview the selected database and then save the repaired database.

You can use the trial version, but it will have limited functionality. For additional features and flawless functioning of your database, buy the paid version of Stellar Repair for MS SQL today. It will ease out your role as a database administrator and help to deal with SQL database issues with success.

Conclusion

A database can go corrupt because of several reasons and in each case, it brings the working of an organization to a standstill. It can lead to extensive data loss and an increase in downtime, causing performance and reliability issues for your business. To maintain data consistency, reduce data loss, and eliminate SQL database corruption, an easy option would be to restore the database to a previous healthy backup. 

If the issue prevails, it would be indispensable to rebuild the SQL database with the corrupt or deleted transaction log files. Using the combination of T-SQL commands – DBCC CHECK DB and REPAIR_ALLOW_DATA can prove effective. Recreating the log file is another thinkable option.  

However, these manual methods are likely to pose a threat to the data integrity, causing data loss. A comparably better idea to deal with SQL data corruption would be to use an effective SQL database repair tool. Notably, Stellar Repair for SQL is a highly recommended tool in this regard. 

It can work actively to rebuild SQL database with corrupt or deleted log files. To get an idea of its functioning, you may use its free trial version. If you find it useful, buying a paid version would be a wise decision, as it will help you to benefit from its accomplished features.