Which join to use?

[przwrz3]

I have to tables:

Fact table Contract:

ID	Type	Value	Date
1	reservation	1000	2022-01-01
2	final	1000	2022-01-01

and Customers:

ID	ContractID	Name	Address
1	1	Doe
2	2	Smith

Each customer can have many contracts signed. Which join should I use in merged query so in the end I will have contract table with name and address of the customer.

[Vijay_A_Verma · Accepted solution]

You will need to use Left Outerjoin. See the working here - Open a blank query - Home - Advanced Editor - Remove everything from there and paste the below code to test (later on when you use the query on your dataset, you will have to change the source appropriately. If you have columns other than these, then delete Changed type step and do a Changed type for complete table from UI again)

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMlTSUSpKLU4tKkssyczPA/IMDQwMQJS+ob6RgZGRUqxOtJIRUCAtMy8xB4c8yJSQ1OISIGVkCJY2gkvHAgA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [ID = _t, Type = _t, Value = _t, Date = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"ID", Int64.Type}, {"Type", type text}, {"Value", Int64.Type}, {"Date", type date}}),
    #"Added Index" = Table.AddIndexColumn(#"Changed Type", "Index", 0, 1, Int64.Type),
    #"Merged Queries" = Table.NestedJoin(#"Added Index", {"ID"}, Customers, {"ID"}, "Table1", JoinKind.LeftOuter),
    #"Expanded Table1" = Table.ExpandTableColumn(#"Merged Queries", "Table1", {"Name", "Address"}, {"Name", "Address"}),
    #"Sorted Rows" = Table.Sort(#"Expanded Table1",{{"Index", Order.Ascending}}),
    #"Removed Columns" = Table.RemoveColumns(#"Sorted Rows",{"Index"})
in
    #"Removed Columns"