SQL Server DBCC CHECKDB command is the database check command that scans the database and its objects for examining their physical and logical integrity. If you run this command and it reports errors, it generally implies database corruption. In such situations, you need to restore from backup. However, if no backup is present or you find it damaged or not updated, you should use MDF Repair applications.

Consider a situation; you run alter table command on database in order to change a column that is not null to null. You encounter erroneous results and either you receive unexpected records with null columns or the database becomes unavailable, marking error 644 in SQL Server error log. After this, when you run DBCC CHECKDB command to check database consistency, the following corruption error is displayed:

Server: Msg 8934, Level 16, State 2, Line 1
Table error: Object ID 1977058079, index ID 1. The high key value on page (1:77) (level 0) is not less than the low key value in the parent (0:1), slot 0 of the next page (1:82).
Server: Msg 8933, Level 16, State 1, Line 1
Table error: Object ID 1977058079, index ID 1. The low key value on page (1:78) (level 0) is not >= the key value in the parent (1:75) slot 2.

The above issues are observed is specific to SQL Server 2000 columns is a clustered index key.

Cause

Possible causes are:

•    Column status synchronization issues between sysindexes system table and syscolumns system table
•    Column is a clustered index key that is null

SQL Server fails to perform correct modification and results corruption.

Solution

To fix these errors, try these steps:

•    Run DBCC DBREINDEX or DBCC CHECKTABLE command with REPAIR_REBUILD option
•    Try running ALTER TABLE command to change the column from not null to null
•    Check database consistency using DBCC CHECKDB command. If it reports corruption, use REPAIR_ALLOW_DATA_LOSS option. But it causes data loss, so it is safe to use commercial master database file recovery applications. These are read-only applications that scan damaged SQL databases and restore them with original content and view.

Stellar Phoenix SQL Recovery is a robust tool to repair damaged SQL Server databases. It supports recover mdf for SQL Server 2000 and 2005. This software provides self-descriptive interface and restores all database objects including tables, user defined data types and functions, triggers, stored procedures, views, rules etc. This MDF Recovery software is compatible with Windows Vista, XP, 2003, 2000, and NT.