How to Effectively Update Entries in SQL Server Using GUIDs From Different Tables

Learn how to select and update records in SQL Server when dealing with GUIDs from different tables. This step-by-step guide simplifies the process and dispels common misconceptions about GUID comparisons.
---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How to select/update only same GUID from different tables

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Effectively Update Entries in SQL Server Using GUIDs From Different Tables

Dealing with GUIDs (Globally Unique Identifiers) in SQL Server can be tricky, especially when you need to update records in one table based on the values from another. If you've ever found yourself wondering how to perform such updates or if GUIDs can be compared, you're not alone. In this post, we will explore how to efficiently select and update data when working with GUIDs from different tables in SQL Server.

Understanding the Situation

Here’s the scenario we are looking at:

You need to update a specific column in one table ([A].[Sch].[Box] in our example) based on matching GUIDs from another table ([B].[Sch.Boxes]).

You've attempted to use CONVERT() and CAST() functions but are facing difficulties achieving the desired updates.

Common Misconceptions about Comparisons

Before we dive into the solution, let's clarify a common misconception: GUIDs can indeed be compared in SQL Server. The UNIQUEIDENTIFIER datatype allows for direct comparisons without the need for converting or casting, which simplifies the process considerably.

Step-by-Step Solution

1. Using an UPDATE Statement with a JOIN

To update records in your table based on the GUIDs from another table, you can utilize a simple UPDATE statement combined with a JOIN. Here’s how to do it:

SQL Query Example:

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

Explanation:

UPDATE T1 specifies the target table (alias T1 corresponds to [A].[Sch].[Box]).

SET [FFType_Id] = 5 defines the column that will be updated.

The FROM clause contains the JOIN, which matches records from the two tables where the Ids are equal.

2. How This Works

The JOIN operation links rows from the two tables based on the Id column, allowing SQL Server to identify which records in [A].[Sch].[Box] need to be updated.

The UPDATE statement is then applied only to those specific entries that satisfy the join condition.

3. Benefits of This Approach

Simplicity: You no longer need to use casting or converting, which can slow down performance and complicate your query.

Efficiency: Updating only relevant records via direct comparisons reduces the risk of unintended changes in your database.

Conclusion

When updating records in SQL Server utilizing GUIDs from different tables, you can achieve efficient and clear operations by using JOINs with your UPDATE statements. Remember that GUIDs can be compared directly, so no casts or conversions are necessary—this will streamline your SQL queries considerably.

Feel free to reach out with any further questions regarding SQL Server or if you encounter any issues while updating your records. Happy querying!