How to patch SQL Server?

Patching Microsoft SQL Server involves updating your SQL Server instance to the latest Service Pack (SP), Cumulative Update (CU), or Security Update (SU). Here's a detailed step-by-step guide:

Step 1: Preparation

1. Identify Current SQL Server Version:

   • Open SQL Server Management Studio (SSMS).
   • Run the following query to check the current version:

     SELECT @@VERSION;

   • Note the Edition, Version, and Service Pack level.

2. Backup All Databases:

   • Open SSMS.
   • For each database:
     1. Right-click the database → Tasks → Back Up.
     2. Choose "Full" backup type and save the backup to a secure location.
   • Don't forget to back up the master, msdb, and model system databases.

3. Check Compatibility:

   • Review the patch notes for the update you plan to install to ensure compatibility with your system (OS, hardware, other software dependencies).

4. Verify Service Account Permissions:

   • Ensure the SQL Server service account has sufficient permissions to apply updates.

5. Disable Jobs and Maintenance Plans:

   • Temporarily disable SQL Server Agent jobs and maintenance plans to avoid conflicts during the update.

6. Review Downtime Requirements:

   • Patching usually requires a restart of SQL Server services or the server itself. Plan accordingly to minimize disruption.

Step 2: Download the Update

1. Locate the Latest Updates:

   • Visit the SQL Server Builds Page to find the latest Cumulative Update (CU) or Service Pack (SP) for your version.

2. Download the Update:

   • Choose the appropriate update for your SQL Server edition and version (Enterprise, Standard, Developer, etc.).

3. Verify the Checksum:

   • Verify the downloaded file's checksum to ensure it hasn’t been corrupted during download.

Step 3: Install the Update

1. Run the Update Installer:

   • Double-click the downloaded .exe file to launch the SQL Server update installer.

2. Accept License Terms:

   • Follow the on-screen prompts and accept the license agreement.

3. Select Instances:

   • The installer will detect installed SQL Server instances. Select the instance(s) you want to update.

4. Check Features:

   • Confirm which features (Database Engine, Analysis Services, Reporting Services, etc.) will be updated.

5. Perform System Checks:

   • The installer will run checks to ensure prerequisites are met. Address any errors or warnings.

6. Begin Installation:

   • Click "Update" to start the installation. The process may take several minutes to hours, depending on your system.

7. Restart Services or Server:

   • After installation, the SQL Server services may restart automatically. If prompted, manually restart the server.

Step 4: Post-Update Tasks

1. Verify Update Installation:

   • Run the following query in SSMS to confirm the new version:

     SELECT @@VERSION;

2. Check System Functionality:

   • Test critical queries, stored procedures, and applications to ensure they function as expected.

3. Re-enable Jobs and Maintenance Plans:

   • Re-enable SQL Server Agent jobs and maintenance plans.

4. Check Logs:

   • Review the SQL Server error logs and Windows Event Viewer for any issues during the update.

5. Update Documentation:

   • Record the new SQL Server version, patch details, and installation date.

Tips & Best Practices

• Always test updates in a non-production environment first.
• Use a dedicated patch management tool, such as Windows Server Update Services (WSUS), for larger environments.
• Stay updated with Microsoft’s release cycles to plan patches proactively.
• Monitor forums or communities for potential issues reported by other users.