Forum Discussion
Merge queries. How replace a row?
I have two queries with the exact same columns. I would like to replace one row record in my main data table with a row record from a second table. I have an index column in both tabels. I woud like to replace index row 23655 in my main data table with row 23655 in my 2nd data table. How would I acoomplish this? I thought merge would work, but I can't figure it out.
If my understanding of the problem is correct, this would probably be the easiest option:
1) Append the long table to your table that holds the replacements
2) Check the index column and remove duplicates
Removing duplicates will keep the first row it finds in a table. This should also be fast.
6 Replies
You could filter out the row in the main query and then use append queries to add the row from the 2nd.
stretcharm Thanks. Yes that would work, but I could potentially have a few hundred random rows I would like to replace and I would like to find a more automated solution where the rows in one table could simple replace the rows in the other table and use the index column as the common column to identify which rows to replace.
You can use a Left Anti to get a data set from the first list that doesnt have rows in the 2nd then append the 2nd.
You could also create a function to replace values, but I suspect this will be very slow on a large dataset.
https://msdn.microsoft.com/en-us/query-bi/m/table-replacevalue
This is a useful blog from cwebb that uses Table.AddKey to improve merge performance.
https://blog.crossjoin.co.uk/2018/03/16/improving-the-performance-of-aggregation-after-a-merge-in-power-bi-and-excel-power-query-gettransform/
https://msdn.microsoft.com/query-bi/m/table-addkey
