Joining 2 SharePoints list in Power Automate

Question

I am wondering if anyone has a solution for this issue that I am facing. I have finished building a repeating table solution involving 2 SharePoint lists.

List A - This is the main list where the form is hosted to do all the data entry.

List B - This is the list that handles repeating data. It has a column named Base_ID that contain the matching ID from List A (there could be 10 items in List B that goes with 1 item in List A).

What I am looking to do is, create a flow that will get all the data from both lists and do (what you would do in MySQL) is a left join.

Now I did find https://powerusers.microsoft.com/t5/Using-Flows/Merging-two-datasets-in-Power-Automate/td-p/944323 and https://powerusers.microsoft.com/t5/Building-Flows/Join-Two-Datasets-in-Flow/td-p/354458 and I have seen comments regarding performance.

Does anyone here know if there is a faster way to do all of this?

Answer 1

You may want to explain the need to have the data all in one list.

This looks like a parent/child relationship, with multiple records in list B relating to one item in list A. I would just leave this alone.

If you want to build forms with this data, that is no problem with PowerApps. You can build screens that show the parent item and a table of all related items by filtering list B with the ID from the List A item. You can add/remove/edit items from List B in PowerApps easily.

If you want to run reports on the data with Excel and Power BI, pull the two list as separate queries and do a merge (ie join) in the Query editor.

That way you can keep the data normalized and avoid duplication of values.

Edit after comment : To join the data from the two lists, so you can compose an email notification, you can use the following approach:

Use Get Items from list A that require processing
for each item in the list (Outer loop)
   Get items from list B where the ID matches the A item ID
   for each item returned from list B (inner loop)
       write item details into a collection
   next item from list B (end inner loop)
   send notification with item details
next item from list A (end outer loop)

This kind of processing is not hard to do and unless you have thousands of records it will not take too long to process.

Answer 2

You can accomplish this by creating a flow in Microsoft Power Automate that retrieves the data from both lists and then performs a join operation on the data.

Here's an example of how you can set up the flow:

Use the "Get items" action to retrieve all the items from List A and List B. Use the "Join" action to join the two lists based on the "Base_ID" column. The "Join" action will output a new array that contains all the items from List A along with the matching items from List B. Use the "Create item" action to add the joined items to a new list, or use the "Update item" action to update the items in List A with the data from List B. You can also use the "Apply to each" action to loop through the joined items and perform additional actions on each item.