SQL Database Corruption Causes, Errors & Best Possible Solutions
Want to prevent database tables and objects then, read this article till the end and learn SQL database corruption causes, errors and solutions.
“I had a data file & I wanted to attach that MDF file to MS SQL Server 2014. Whenever I try to attach this file, I always receive the following error message:
The header of the file ‘…/MSSQL/DATA/yyyy_data.mdf’ is not a valid file header of the database. It also displays that the FILESIZE property is incorrect. After searching through the net, I found that the MDF file has corruption in its header part. I tried various expert solutions from various forum sites to solve it but I failed, and thus I am getting the same error message again & again. I would like to know that, what are the reasons for this database corruption in SQL Server. Any help will be highly appreciated. Thanks!”
Table of Content:
The following technical write-up will discuss the corruption issues in the SQL Server database and reason behind it. Let us explore the table of content before going further:
Let’s Talk About SQL Server System Database Corruption in Detail
The SQL Server stores its physical data in .mdf file & the very first page of this file comprises of the header information. This header page keeps the information about the entire DB like size, file signature and much more. In order to attach this MDF file in SQL Server, several users encounter errors like Microsoft SQL Server header error 5172, SQL Server Error 2, SQL Server Error 5171. This type of corruption in SQL server generally comes when the SQL MDF file becomes damaged. Due to this error, the information in the header gets mismatched & thus takes the database into the inaccessible state.
SQL Database Corruption Causes & its Prevention
- Don’t Reboot Server
By rebooting the server you can only help & fix the minor issues from the Operating system’s end. If there is an issue from the server’s end, then rebooting is not at all an appropriate mean of solving SQL Server data corruption. Rebooting the system will only transfer the database in offline mode & will detect database in SUSPECT mode. This can even lead to a worse situation.
- Don’t Shut Down Server
Once identifying the master database corruption in SQL Server, every user tries to shut down the Server, which is not an appropriate solution, as it may make the database inaccessible.
- Don’t try to Detach / Reattach Database
If SQL DB is corrupted, then reattaching & detaching the database will make the process even worse.
- Don’t Upgrade SQL Server
Do not upgrade the server to repair SQL database. As it is not an accurate method because updating or upgrading the version will only create new hurdles.
- Don’t Run Any Repair Commands
DBCC CHECKDB command should not be run unnecessarily. If all other method fails to work then the only user should opt this manual way. In many cases, this command payoff users with permanent loss of data. Thus, while executing this command, you should be technically strong & have knowledge of its correct syntax.
There are following prevention methods to eliminate SQL Server system database corruption.
- Enter data validation
- User should change Application password on the regular basis
- Do not make any unnecessary functionalities, hence prevent them from hacking
- Best approach is to use a web application firewall while dealing with SQL database so as to fix
- SQL Database corruption causes from any malicious attack
Manual Technique to Fix SQL Server Database Corruption
The below-stated techniques can be used only for minor level corruption, hence it is suggested to not expect immediate results. This method only depends on the level of corruption, since it is no more effective to deal with the certain level of corruption. Users can follow some of the manual methods to resolve SQL Server data corruption:
- For fixing the issue one can use the log file or a backup file to repair SQL Database, but in some of the cases due to the high corruption, this method may also do not work.
- The user can also try database console command DBCC REPAIR and DBCC CHECKDB to fix SQL database corruption, this particular method requires a lot of technical knowledge & grip on command. It is thus suggested that non-technical users should not go for this solution. This method is only useful in case of minor level corruption.
How to Fix SQL Server System Database Corruption Using Software
Users can try SQL Recovery Software to repair corrupt SQL database files(MDF & NDF). It allow to recover & scan triggers, rules, tables, functions, stored procedure etc. The understandable User Interface of this tool makes it possible to recover various other SQL objects present in MDF & NDF file without any hassle.
Steps to remove SQL database corruption are as follows;
Step 1:- Launch the software to repair & open MDF file
Step 2:- In the Scan Options, you can select any one according to the need. After that select the SQL Server version.
Step 3:- As soon as the MDF file gets uploaded, click on the database object to preview the recovered database.
Step 4:- The software will let you export the recovered MDF file in two ways:
1. Export as SQL Server Database
2. Export as SQL Server Compatible Script
It all depends on the user in which format he/she wants the recovered data file.
Users can also check the “With the only schema” & “With Schema & Data” option according to its need.
Step 5:- At last, click on Export button.
In this article, we have discussed SQL database corruption causes such as power failure, sudden shutdown, hardware failure, malware attacks etc. Besides this, we also illustrate types and prevention for the database corruption in SQL Server.
Frequently Asked Questions
There are multiple reasons for corrupting SQL data such as:
1. Hardware Failure
2. Software Problem
3. Human Miss-Operations
4. Virus Attack
DBCC CHECKDB is used to check the corruption in the SQL Server database and to fix minor problems. To check, you can follow the syntax – DBCC CHECKDB (database_name).