How to Migrate Data from SQL Server to Oracle Database?

The conversion of data from one database management system to another can be a difficult process, particularly when migrating from SQL Server to Oracle Database. In this article, We will learn about How to migrate data from SQL Server to Oracle database by providing clear and detailed procedures.

Overview of SQL Server and Oracle

• There are many DBMSs in the world, but SQL Server and Oracle are two of the most commonly used in the industry.
  
• SQL Server is a product of Microsoft Company is considered to be very user-friendly, programs can easily interface with other Microsoft products.
  
• Of all the databases, Oracle Database is highly revered for its availability, flexibility, and functionality density.
  
• Migration from SQL Server to Oracle involves converting data that should be done efficiently to avoid problems in the future as the programs transform to fit the new environment.

Steps to Migrate SQL Server to Oracle with Oracle SQL Developer

1. Create the mwrep User

First, to categorize assets we have to create a user called 'mwrep' in the Oracle database instance that will own migration repository.

CREATE USER mwrep IDENTIFIED BY password;
GRANT DBA TO mwrep;

2. Create the Migration Repository

Next, the migration repository has to be created using Oracle SQL Developer. This data store will contain meta information regarding migration process and its results.

1. Open Oracle SQL Developer.
2. Go to Tools > Migration > Repository Management.
3. Choose Create Repository and, from the list, follow through the steps to attach to your Oracle database and create the repository.

3. Capture Exported Files of SQL Server

Export the schema and data of the Microsoft SQL Server database into flat files. To create these files, you can use SQL Server Management Studio (SSMS).

1. Open SSMS.
2. Right-click the database you want to export.
3. To export data to flat files go to Select Tasks > Export Data and then click on the export button located on the toolbar to follow the wizard.

4. Check Conversion Preferences

Always ensure that when you are using Oracle SQL Developer you need to have the right conversion preference set.

1. Go to Tools > Preferences > Migration.
2. Verify settings under Capture, Convert, and Generate tabs.

5. Convert the Captured Database

Capture and convert the exported SQL Server files into an Oracle-compatible format.

1. Go to Tools > Migration > Capture.
2. Import your SQL Server files and convert the schema according to the prompts.

6. Generate the Oracle Database

Create the Oracle database by using the schema that you have transformed.

1. Go to Tools > Migration > Generate.
2. Choose your migration project and, after following the steps, obtain the Oracle schema.

7. Specify Offline Data Move Preferences

In case of necessity, it may be necessary to set up preferences regarding the moving of large amounts of data offline.

1. Go to Tools > Preferences > Migration > Data Move.
2. Adjust settings to suit your data size and transfer speed requirements.

8. Analysis and Estimation

Pause to reflect, to estimate the time and resources needed for this grand migration. Consider:

1. Data Volume: The vastness of your data ocean.
2. Complexity: The intricacies of tables, views, and stored procedures.
3. Dependencies: The relationships that bind your data.

9. Import the Data

As the new Oracle database you have to import data into it.

1. Transfer data with the help of the Data Move function of Oracle SQL Developer.
2. After that, use the arrows to proceed with the steps to move the data from SQL Server data to Oracle.

10. Test and Deployment

Once data has been migrated it is important to carry out several checks which will determine whether a particular migration was successful or not.

1. Check Data :Make sure every last bit of data has arrived intact.
2. Test Applications: Test applications to ensure that they run well with the new Oracle database.
3. Performance Testing: Look out for bottlenecks and resolve them to achieve optimal performance.

11. Backup SQL Server and Oracle in Advance

It is always recommended to develop copies of both your SQL Server and Oracle databases before provoking the transition to avoid the loss of crucial information.

1. SQL Server: Using SQL Server Management Studio, click Tasks > Back Up to generate a backup.
2. Oracle: Make a backup using RMAN(Recovery Manager) or Oracle SQL Developer and keep your data in an impregnable castle of safety.

Example 1: Exporting Data from SQL Server

In SSMS, exporting data involves the following steps:

1. Right-click the database you want to export.
2. Select Tasks > Export Data.
3. Choose SQL Server Native Client as the data source.
4. Specify Flat File Destination for the output.
5. Select the tables and views to export.
6. Complete the wizard to generate flat files.

Example 2: Importing Data into Oracle

In Oracle SQL Developer, follow these steps:

1. Go to Tools > Migration > Data Move.
2. Select the migration project.
3. Specify the data files to import.
4. Follow the prompts to complete the data import process.

Conclusion

Overall, Migrating from SQL Server to Oracle involves several crucial steps, from creating the migration repository to importing data and performing thorough testing. By following the outlined procedures, you can ensure a smooth and successful transition. Always remember to back up your databases before starting the migration to safeguard your data.