Cannot update record in SQL

[Vstar19]

So, i have spent 3 hours trying to resolve something that i have done before and its really bugging me. 

I have a sql table, as below

ID    | Name | SysID | RequestID

123 | ABC     |          | 1

456 | def      |           | 2

etc

Note, the Sys ID is blank for every cell. I wish to update this sys ID. 

I have written a flow that gets all the rows from this SQL Table. This works fine. 

Then i have an apply to each where I get the ID of each record and use that that ID to get the SysID from an external table (i used the HTTP action for this). I then store the value of the sysID in a compose called 'SysID'. This part works fine. 

So i have successfully got the SysID for every record. 

In the same apply to each i use the Update row to update the SQL Record, 

When i update the row, for the Row ID, i select the Request ID and for the SysID i select Sys ID. 

However, every time i run the flow, i get the below error : Incorrect syntax near 'WHERE'.
clientRequestId: a3195ad3-bd9d-466e-b5ed-fee408906f86 

I havnt a clue what it means, or why its appearing?. What have i done wrong?

Thanks