The blog is all focused on the SQL Server database file (MDF) that how it is prone to corruption and what are the measures that an SQL administrator can take to repair MDF file.
An SQL Server stores the complete database schema along with data in its primary database file MDF. There is another file also of SQL Server database named LDF file which stores database logs and other files. But most commonly, when one says that SQL database is corrupt, then it is the corruption occurred in the MDF file. With continuous updates and modifications in operations in SQL database, the chance of inconsistency in data increases. The database file contains crucial information and certainly there is great vulnerability to its corruption.
There could be different reasons for a corrupt MDF file which we will be mentioning further. As in the other databases, corruption hampers the work or stuck the work in middle as it restricts the access to data stored in the respective database. In such cases of corrupt databases, the users encounter a certain error while trying to access that particular database. There is a need to repair MDF file which is corrupt due to any possible reason.
There could be one or more reasons given below which can be responsible for the MDF file corruption:
As mentioned, it cannot be certain that a particular reason is responsible for the corruption. So, once the corruption is confirmed, one should look for the feasible solutions as per their needs.
We can try the free manual solutions first to repair the corrupt SQL Server database. There is no harm if you are having a recently taken backup of your corrupted SQL database and restoring the database from it. But if the backup is taken much time before, then you will be surely going to miss the later add-ons data and information from it even if you restore the backup successfully. So, it is a good practice to take the backup of your database regularly to avoid such situations.
As the backup way is not working now, so we can move ahead to the next manual solution to repair the database. SQL Server Management Studio is the next help. Users can run scripts or query in this in-built application and repair the corrupt SQL database.
There are DBCC statements or Database Console statements (in Transact-SQL) using which administrator can inspect the physical as well as logical consistency of a Microsoft SQL Server database. These statements also fix any issues with the SQL Server database.
This DBCC CHECKDB command performs the combined functions of all three commands (DBCC CHECKALLOC, DBCC CHECKCATALOG and DBCC CHECKTABLE) with single statement only.
DBCC CHECKALLOC – To check the disk space allocation structures for a database
DBCC CHECKTABLE – To check the integrity of the pages and the structures that build indexed view or tables
DBCC CHECKCATALOG – To check the consistency of an online database
To repair the SQL Server database, start the SQL Server Management Studio and run this query:
DBCC CHECKDB
[ ( database_name | database_id | 0
[ , NOINDEX
| , { REPAIR_ALLOW_DATA_LOSS | REPAIR_FAST | REPAIR_REBUILD } ]
) ]
[ WITH
{
[ ALL_ERRORMSGS ]
[ , EXTENDED_LOGICAL_CHECKS ]
[ , NO_INFOMSGS ]
[ , TABLOCK ]
[ , ESTIMATEONLY ]
[ , { PHYSICAL_ONLY | DATA_PURITY } ]
[ , MAXDOP = number_of_processors ]
}
]
]
As discussed earlier there is no benefit for restoring database from backup if it is not the recent one. And there are chances of data loss while backing up the database manually. Running scripts in SQL Server Management Studio requires technical knowledge and this method is bit complex one. If the MDF file is severely corrupted, then this method would not be successful in such condition.
For quick and easy repair of MDF files, choose the automated professional tool namely SQL Database Repair tool which repairs corrupt SQL database files within minutes and restore tables, triggers, objects and other data from the database to server again. It keeps originality intact throughout the repair process. It includes its free demo version and supports all SQL Server versions. Try the advanced repair tool for your ease.
