Best Practices for SQL Server Forensics Using ApexSQL Log

Step-by-Step Guide: Recovering Deleted Rows with ApexSQL LogRecovering deleted rows from a SQL Server database can be critical after accidental deletions, malicious actions, or application bugs. ApexSQL Log is a specialized tool that reads SQL Server transaction logs to audit, undo, or redo data changes. This guide walks through recovering deleted rows using ApexSQL Log, from preparation and prerequisites to execution and verification.

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Before you begin — prerequisites and safety

• Ensure you have a recent backup of the database (full, and ideally log backups) before performing any recovery actions.
• You need appropriate permissions: sysadmin on the SQL Server instance or membership in roles allowing access to transaction logs and the database.
• The target database must be in FULL or BULK_LOGGED recovery model for transaction log-based recovery to be effective (simple model truncates log and may prevent recovery).
• Install ApexSQL Log on a machine that can connect to the SQL Server instance.
• If recovery involves point-in-time or log backups, collect all relevant backup files and ensure transaction logs are intact from the time of deletion until now.

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Overview of the recovery approach

ApexSQL Log analyzes the transaction log (and optionally log backups) to locate the DELETE operations that removed rows. It can then generate a SQL script that reverses those deletes (INSERTs), or directly execute the undo against the database. The typical steps:

1. Attach ApexSQL Log to the server/database and select the transaction sources.
2. Filter results to find the specific DELETE operations/rows.
3. Review the changes and generate an undo (INSERT) script.
4. Apply the script in a controlled manner (test first, then production).
5. Verify recovered data and audit the incident.

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Step 1 — Connect ApexSQL Log to your SQL Server

1. Launch ApexSQL Log.
2. Click “New Project” (or similar) to start analyzing a database.
3. Provide SQL Server instance name, authentication method (Windows or SQL Server), and credentials.
4. Choose the target database from the dropdown list.
5. Select the transaction log sources:
   • Online transaction log (directly read current LDF).
   • Transaction log backups (add .trn files).
   • Full and differential backups (if you need to restore to a point where logs are continuous).
6. Confirm the selected time range if prompted (you can restrict to a timeframe around when deletion occurred).

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Step 2 — Configure search filters to find deleted rows

To avoid scanning irrelevant transactions, narrow the search:

• Set operation type to DELETE.
• Set the time window (from around when deletion likely occurred).
• Filter by database and specific table(s).
• If you know the user or application that performed the delete, add a filter on Login/User.
• Use WHERE clause filters (e.g., based on known key values) to find rows with specific IDs or column values.

Example filters:

• Operation: DELETE
• Table: dbo.Orders
• Time range: 2025-08-25 09:00 — 2025-08-25 11:00
• Login name: app_service_account

Run the search.

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Step 3 — Review identified transactions and rows

ApexSQL Log will list transactions that match your filters. For each transaction you’ll typically see:

• Transaction ID and timestamp
• SQL statement or operations (DELETE FROM dbo.Table WHERE …)
• User/login that executed the transaction
• List of affected rows or before/after values for columns

Carefully review the results to confirm you’ve identified the correct deletion event(s). Pay attention to transactions that include multiple operations (updates, inserts, deletes) to ensure you undo only what’s needed.

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Step 4 — Generate undo script (INSERT statements) or replay

ApexSQL Log offers options to undo changes:

• Generate a SQL script that inserts deleted rows back (recommended for review/testing).
• Generate a script that replays transactions (REDO) or undoes them automatically against the chosen database.
• Export results to CSV or other formats for analysis.

To generate an undo script:

1. Select the DELETE transactions/rows you want to restore.
2. Choose “Undo/Recover” or similar and select “Generate rollback script” or “Generate undo as INSERT”.
3. Configure options:
   • Target database/schema/table (ensure this is correct).
   • Whether to generate full INSERT statements with all column values or partial columns (choose all columns to preserve original data).
   • Include identity values if table has identity column (use SET IDENTITY_INSERT ON/OFF around inserts).
   • Handle constraints: you may need to temporarily disable foreign keys or check constraints, or insert in parent-child order.
4. Save the generated script to a file.

Example of common script pattern generated:

SET IDENTITY_INSERT [dbo].[Orders] ON; INSERT INTO [dbo].[Orders] ([OrderID], [CustomerID], [OrderDate], [Total]) VALUES (12345, 'CUST01', '2025-08-25 09:17:32.000', 199.95); SET IDENTITY_INSERT [dbo].[Orders] OFF; 

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Step 5 — Test the undo script in a safe environment

Never run the undo script directly on production without testing.

1. Restore a recent full backup of the database to a test instance or create a copy of the production database (detach/attach or copy-only backup/restore).
2. Apply the generated INSERT undo script in the test environment.
3. Verify:
   • Recovered rows match the original values.
   • No constraint violations or data integrity issues.
   • Referential integrity for related tables is preserved.
4. If the script causes conflicts (duplicates, FK violations), adjust:
   • Modify INSERTs to skip existing rows or use MERGE semantics.
   • Insert parent rows first, then child rows.
   • Temporarily disable constraints, then re-enable after fixes.

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Step 6 — Apply recovery in production

Once validated:

1. Schedule a maintenance window if necessary.
2. Take a fresh full backup of production before applying changes.
3. Disable non-critical processes that may interfere (optional).
4. Run the undo script on production. If the script includes SET IDENTITY_INSERT or constraint toggles, ensure correct sequencing.
5. Monitor for errors; if errors occur, stop and analyze logs rather than proceeding blindly.

Alternative: let ApexSQL Log directly execute the undo within the tool (if you trust it and have operator permissions). This can be faster but offers less manual review control.

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Step 7 — Verify and audit recovery

• Run queries to confirm recovered rows exist and values are correct.
• Check related tables for referential consistency.
• Review SQL Server error logs and application logs for any issues during the recovery.
• Generate an audit report from ApexSQL Log showing which transactions were undone and by whom (tool, user). Keep this for compliance.

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Troubleshooting common issues

• Transaction log truncated (SIMPLE recovery) — missing older log records may make recovery impossible. If so, restore from backups to a point-in-time before deletion.
• Partial row data or compressed/encrypted logs — ensure ApexSQL Log supports the log type and any encryption keys are available.
• Identity or constraint conflicts — use SET IDENTITY_INSERT and careful ordering of statements.
• Large number of deleted rows — consider batching INSERTs and monitor transaction log growth during recovery.

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Best practices to reduce future risk

• Keep the database in FULL recovery model if point-in-time recovery is required.
• Implement regular full and log backups and test restores frequently.
• Enable auditing and transaction logging for critical tables.
• Put role-based safeguards and confirmation steps in applications before destructive operations.
• Periodically practice recovery drills using tools like ApexSQL Log to ensure procedures work.

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When to involve DBAs or support

• If transaction logs are missing or corrupted.
• If the deletion spans large data volumes and could impact performance.
• If there are complex referential dependencies across many tables.
• If legal/compliance implications require formal chains of custody for recovery actions.

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Recovering deleted rows with ApexSQL Log is powerful but must be done methodically: identify the correct delete events, generate reviewed undo scripts, test in a safe environment, then apply and verify in production. Following the steps above helps restore data accurately while minimizing risk.