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Learn how to effectively store files in SQL Server using Delphi 10.3 and ADOQuery component. Get step-by-step guidance and best practices for handling files.
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How to Store Files in SQL Server Using ADOQuery Component with Delphi

Storing files in a SQL Server database can be a challenging task, especially when using tools like Delphi. If you're trying to save different file types, such as PDFs, text documents, and more, into a SQL Server table, you might find yourself in a bit of a conundrum. However, this guide will guide you through the process of storing files in a varbinary(max) column of SQL Server using the ADOQuery component in Delphi 10.3.

Understanding the Problem

When trying to store files directly in SQL Server, the common approach is to create a table that includes a column for the file extension and another for the file itself in a binary format. In this case, the current structure of your Personal_Files table includes:

A varchar column to store the file extension.

A varbinary(max) column to store the actual file data.

The initial attempt at storing files involved encoding the file as a Base64 string and attempting to save that string into the database. However, the challenge arises because the parameter set by the ADOQuery component does not directly accept TStream type, leading to incorrect storage.

The Solution: Step-by-Step Approach

Fortunately, there's a straightforward solution to this problem! Below, we'll break down the steps needed to successfully store files in your SQL Server table using Delphi.

Step 1: Setting Up Your Streams

You need to create two streams before you can send the file to the database:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Load the File into the Stream

Instead of encoding the input stream to Base64, load the file directly into the output stream in binary format:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Inserting Data into SQL Server

Now, we can insert the file data into your SQL Server database. The most important change here is to use LoadFromStream method on the Parameters.Items to directly pass the output stream:

[[See Video to Reveal this Text or Code Snippet]]

Important Note

While the solution provided above resolves the issue of storing files in the database, it's essential to consider that storing files as binary data in a SQL Server database is not typically recommended for performance reasons. It's usually advisable to store large files on a filesystem and keep only the path and metadata in the database.

Conclusion

Storing files in SQL Server using Delphi's ADOQuery component is achievable by leveraging the LoadFromStream method, which directly accommodates binary data types. By following the steps outlined above, you can efficiently handle file storage while being mindful of the considerations surrounding this practice.

Remember to always consider the recommended practices for better performance and data management in your applications. Happy coding!