Repair Corrupted System Tables in SQL Server With Best Methods

Database administrators and users often encounter various issues in the database. However, these issues are not limited to only the major database components, but also in system objects as well. One such issue is the corrupted system tables in SQL Server. In this write-up, we will discuss a similar issue and further suggest the best ways to resolve the issue in a much more effective way.

Before we begin, we will first learn more about the sys tables in SQL Server. 

What are System Tables in SQL Server? Overview

When we talk about the system tables in the database, they can be defined as the internal tables that are mainly managed by SQL Server. These tables are created in SQL and are further responsible for storing the crucial information and details about databases and their operation. They also store the metadata in the SQL Server database. Here are some of the use cases where sys tables in SQL Server are used:

• At the start of SQL Server
• During the creation of a table or database in SQL
• While users log into the database
• During Backup and Restore in SQL Server
• In Disaster Recovery operations

By looking at these use cases, we can understand how important these tables are for the users. Now, these are only a few of the uses of the system tables. Let’s take a closer look at the responsibilities of SQL Server system tables. 

Why Sys Tables in SQL Server Are Important?

We will now take a look at several reasons to learn the importance of these tables. 

• The major importance is that these tables control and manage the SQL Server database structure entirely. 
• They are also responsible for deciding who can access the database and the data residing in it. 
• The next reason system tables are important is that they are responsible for running and starting SQL Server. 
• These tables also help with various operations, like backup/ restore in the database. 

Managing the entire workflow of the database can be considered the primary role of the system tables. This is why it becomes important to keep these tables healthy and secure. However, in many situations, these tables end up getting corrupted. Corrupted tables can lead to SQL Server databases not working properly and can cause several issues for the users. Let’s now take a look at the possible causes that lead to corruption in the sys tables in SQL Server. 

What Causes Corruption in System Tables in SQL Server?

There can be different reasons that can lead to corruption or other issues in the database. We will take a look at these causes one by one to understand them better and further understand how these can be resolved in a much easier way. 

• One of the causes for a corrupted system table in the SQL database is due to an abrupt shutdown or sudden power outage. 
• The next reason for the corruption in the sys table is the issues with the disk or storage. Bad sectors or hard drive failures often lead to corruption in system tables.
• If there is corruption in the file systems, it will also result in a corrupted system table in the SQL Server database. 
• Viruses, malware attacks, or ransomware attacks are also some of the common causes for this issue. 

After understanding these issues, we will now proceed with the solutions that will help repair corrupted sys tables in the database. 

How to Repair Corrupted System Tables in SQL Server? Best Methods Explained

Here, we will discuss a few methods that will help database administrators repair the corruption in system tables. Let’s understand how each method works and how it will help the users. 

Method 1: Use Backups to Restore System Databases

In this method, we will use the backup of a healthy database to restore the system database and repair the corrupted sys table in SQL Server. The steps for this method are given below:

1. The first step is to run the SQL database in Single User Mode. 
2. Next, it is now required to restore the corrupted system database. The command given below will help with that.
   

   RESTORE DATABASE master
   FROM DISK = ‘C:\Backup\master.bak’
   WITH REPLACE;
   

   This command will help restore the master database using the backup. Now, to restore the model and msdb databases, users only have to change the name of the database in the file path specified.

3. Once these steps are completed, it’s now time to restart the database. This way will allow users to restore the database.

Moving on to the next method, let’s see how it can help resolve the issue. 

Method 2: With the Help of a Professional Solution

Along with the manual solutions, one more professional way to deal with this issue. With the help of an expert solution, like SysTools SQL Recovery Tool, it becomes much easier to deal with and repair corrupt system tables in SQL Server.

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Below are the steps that will help with the easy recovery. 

1. Install and run the suggested software. Add .mdf file of the affected database by clicking on the Open Button.
   
   
2. Once you add the file, the tool will scan for corruption.
   
   
3. After the scan, preview the recovered data from the corrupt sys table in SQL Server.
4. Next, click on the export button to save the repaired system tables.
   
   
5. Add authentication details and choose database objects to be exported. Click on Export to repair the corruption easily.
   
   

These easy-to-follow steps will allow users and database administrators to fix the system table corruption quickly and hassle-free. 

Method 3: Use DBCC CHECKDB to Repair Corruption in Sys Tables in SQL Server

The next method we will be using is the DBCC CHECKDB command. This command will help users inspect and detect corruption in the database system tables. This method is helpful to detect and resolve minor damages and corruption within the database. Given below are the steps that will help with repairing the system tables in the database. 

Step 1: The first step is to put the database in single-user mode.

ALTER DATABASE  ‘DBNAME’ SET SINGLE_USER;

Step 2: Run the repair command on the affected database.

DBCC CHECKDB (‘DBNAME’, REPAIR_ALLOW_DATA_LOSS);

This command will repair the corrupted sys tables in the database; however, the major risk with this command is that it might result in permanent data loss of the data residing in the database.

Step 3: Set the database back to multi-user.

ALTER DATABASE ‘DBNAME’ SET MULTI_USER; 

Following these steps, users can recover the system tables from corruption. But the major setback of this method is that it can lead to a complete data loss. This is why using a professional and dedicated repair utility, like the one we suggested, is important. 

Conclusion

With the help of this write-up, we learned more about corruption in system tables in SQL Server. We also discussed the factors that led to this issue in the database. Additionally, to resolve the issue effectively, we have suggested the best ways to repair the corrupt sys tables in SQL Server.