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How to Repair/Fix Corrupt SQL Server Database – Solution Explained

Ashwani Tiwari | Modified: 2021-11-15T13:10:00+05:30| SQL | 7 Minutes Reading

Are you seeking for a technique to repair corrupt SQL server database? Do you wish to use effective method to recover corrupted SQL server database? Users will understand and learn about how to recover the corrupted SQL Server database using a variety of ways. Before we go into solutions, let’s look at some real-world scenarios where users are looking for a way to reinstate SQL database MDF files.

What is SQL Server, Exactly?

SQL Server is a database management system that is mostly utilized by other programs to store and retrieve data. SQL Server, which was create by Microsoft, stores and manages data using three different types of files: Primary Files (MDF), Secondary Files (NDF), and Log Files (LDF).

The .MDF extension is use for primary SQL Server database files. Each database includes a single primary file that stores user data and objects such as Indexes, Columns, Views, Functions, Values, Tables, Keys, Stored Procedures, Triggers, and Default Values, among other things. The database’s initialization information is also stored in MDF files.

Secondary files are not required but are available as .NDF. You can make an endless amount of NDF files based on your needs. NDF files are commonly used to transfer data across numerous discs, but they can also use to hold user data.

The backup files of a SQL Server database known as log files. In the event that the database becomes corrupted, they uses to restore it. The format of log files is .LDF extension and log information storage At least one log file exist in every database.

Also Read: Recover Database from Emergency Mode in SQL Server

The Cause of SQL Database Server Corruption

  • On occasion, a user will overwrite an existing MDF file. This is the root of all corruption. It expands the file size and raises the chance of corruption.
  • Attempting to unlock the SQL Database too many times can result in corruption. It is not uncommon for a user to forget his SQL password and begin making random attempts. SQL Server corruption may result as a result of this.
  • Because this storage has a connection with the SQL Server, a failure in the Flash Drive or Disk drive can cause the entire SQL Database to be corrupt.
  • The SQL Database’s configuration corrupts it at some point. It begins working on the database and prevents access to MDF files.
  • A virus infection can corrupt the entire SQL Database files, resulting in corruption concerns. You can correct it, but it may result in data loss.
  • Internal SQL Database issues can cause MDF files to corrupt. They corrupt the MDF files, which corrupts the SQL Server as a whole.

How to Manually Repair a Corrupted SQL Server Database

With the help of the versatile DBCC Check command, you may restore a database from a corrupted MDF file in SQL Server. It is the sole technique for easily repairing a faulty database in Microsoft SQL Server. In general, there are two situations in which you can use this procedure to repair the SQL Server master database file. Let’s get started!

1. Repair the SQL Server Database when it is in Recovery Mode

When a resource-related issue arises during the recovery procedure, the database enters the Recovery Pending state. The SQL Server database is neither corrupted nor damaged in this circumstance. However, it is inaccessible due to a file or system resource error.
To resolve the SQL Server has a recovery pending status, you must remove the current database and reattach it using a T-SQL query.

2. How to Repair a SQL Server Database that has been Marked as Suspicious or Corrupted

It’s conceivable that the primary filegroup has been corrupt or damage when in Suspect mode. Because of this, the SQL database is unavailable. You must use the DBCC Check command to repair the Suspect database. In this section, we discussed a general approach for effectively resolving SQL database Suspect mode errors. This procedure divides into several steps.

Step 1: Change the SUSPECT Database to Emergency Mode

This option only grants system administrators read-only access to the database. Furthermore, the EMERGENCY State can only establish by sysadmin members. Run the following a question for the screen to create a database in EMERGENCY mode.
ALTER DATABASE DATABASE_NAME SET EMERGENCY
We take database name – ‘testing’ and execute the preceding command.

Step 2: Examine the Damage Level

You must execute the DBCC CHECKDB (DB_Name) query and examine the errors.
DBCC CHECKDB (Database_Name)

Step 3: Repair Command should be Executed

There are three repair modes available with DBCC CHECKDB to restore the database to functioning mode from EMERGENCY mode:

  • REPAIR_FAST

It has the ability to retain backward compatibility syntax. It indicates that SQL Server 2005 database files uses in SQL Server 2008. There are no major repairs carried out. Make sure the database is in SINGLE USER mode rather than EMERGENCY Status if you wish to fix the backward compatibility issue.
Use the following techniques to set the database to SINGLE USER MODE:-

Method 1: By Using GUI

  1. Right-click on the database to choose it.
  2. Select Options.
  3. Select the Restrict Access button from the drop-down menu. SINGLE USER is select, and then OK button pressed.

Method 2: By T-SQL Query

The database type can be set to SINGLE USER using T-SQL. To do so, run the query below in SSMS.
ALTER DATABASE DATABASE_NAME SET SINGLE_USER

  • USE REPAIR_FAST Command

Execute the following SQL Server query to repair the database after setting it to Single USER Mode.
DBCC CHECKDB (N ‘Database_Name’, REPAIR_FAST) WITH ALL_ERRORMSGS, NO_INFOMSGS; GO

  • REPAIR_REBUILD

This SQL database repair command is prefer because it has a low chance of accidental loss. It should, in theory, carry out all of the repairs that REPAIR FAST makes. Additionally, it does various time-consuming fixes, such as rebuilding the indexes. To utilize this, run the query listed below.

Note: Ensure that the database is set to SINGLE USER mode.

DBCC CHECKDB (N ‘database name’, REPAIR_REBUILD) WITH ALL_ERRORMSGS, NO_INFOMSGS;
GO

  • REPAIR_ALLOW_DATA_LOSS

This also conducts the tasks of allocating and de-allocating pages, deleting corrupt objects, and fixing page problems, in addition to repair. This also corrects the database’s structural flaws. This sort of repair, however, invariably results in some data loss. It can also operate in EMERGENCY mode without causing any problems.
DBCC CHECKDB (N’Database_Name’, REPAIR_ALLOW_DATA_LOSS) WITH ALL_ERRORMSGS, NO_INFOMSGS;
GO

Stage 4: Configure the Database to MULTI_USER Mode

After the database has been properly repaired, run the query below to convert the database mode to Multi user mode.
ALTER DATABASE DATABASE_NAME SET MULTI_USER

Repair Corrupt SQL Server Database in a Professional Manner

Another approach is to utilize DataHelp SQL Database Recovery Software for how to repair corrupted SQL server database in an easy and rapid manner. It allows users to repair faulty SQL databases and remove practically all sorts of corruption without affecting the original data. The application also allows users to export the repaired data to a live SQL Server environment on the same network, as well as export SQL Server databases to script files or CSV files.

On addition, the tool may repair corrupt SQL Server databases in 2019, 2017, 2016, 2014, 2012, and earlier versions. Furthermore, when compared to the manual solution, the tool is quite safe to use.

Conclusion

We’ve covered everything there is to know about SQL databases and how they can corrupt in this blog. We reviewed what SQL server is and how to recover data from corrupted SQL server database in the first part. We have attempted to list all of the error messages that a user would encounter while dealing with the corruption. This may assist the user in detecting corruption and resolving the repair corrupt database in SQL server issue in the future.

We’ve also discussed how to detect database corruption quickly. Finally, we talked about how to repair corrupted SQL server database. DataHelp SQL Database Recovery Software is the best, quickest, and safest approach to deal with corrupt SQL Server databases.