T-SQL MERGE Statement Not Updating Rows as Expected in SQL Server 2019
I'm maintaining legacy code that I'm working through a tutorial and I'm using a MERGE statement to synchronize two tables, but I'm running into an issue where certain rows are not being updated as I expect. My source table (`SourceTable`) has the following structure: ```sql CREATE TABLE SourceTable ( Id INT PRIMARY KEY, Name NVARCHAR(100), Value INT ); ``` And my target table (`TargetTable`) looks like this: ```sql CREATE TABLE TargetTable ( Id INT PRIMARY KEY, Name NVARCHAR(100), Value INT ); ``` I have the following MERGE statement: ```sql MERGE INTO TargetTable AS target USING SourceTable AS source ON target.Id = source.Id WHEN MATCHED THEN UPDATE SET Name = source.Name, Value = source.Value WHEN NOT MATCHED THEN INSERT (Id, Name, Value) VALUES (source.Id, source.Name, source.Value); ``` However, when executing this statement, I notice that some records in `TargetTable` are not being updated, even though they have matching IDs in `SourceTable`. I've double-checked that the IDs are indeed present in both tables, and there are no NULL values in the `Id` columns. I'm running SQL Server 2019, and I've tested this on several rows. For example, if `SourceTable` has an `Id` of `1` with a `Name` of 'UpdatedName' and a `Value` of `100`, the corresponding row in `TargetTable` is not updated, despite the expected behavior. The output from the MERGE command shows that it matched the rows but doesn't reflect the updates. I've also tried running the query with explicit transactions and checking for potential locks, but nothing stands out. Additionally, I verified that SET NOCOUNT is not interfering with the results. Any insights into why this might be happening or what I could check next would be greatly appreciated! I'm working on a application that needs to handle this. Any examples would be super helpful. My team is using Sql for this microservice.