I have the following 2 ksqldb streams that I’d like to join based on the invoiceNumber.
<outputing to a new topic the total combined of the 2 streams>

— the InvoiceNumber is the primary key if we can call it that.
— the messages are posted onto the topics, with a key based on the store.id

-- salesbasket
CREATE STREAM salesbasket (
        InvoiceNumber VARCHAR ,
        SaleDateTime VARCHAR,
        SaleTimestamp TIMESTAMP,
        TerminalPoint VARCHAR,
        Nett DOUBLE,
        Vat DOUBLE,
        Total DOUBLE,
        Store STRUCT<
            Id VARCHAR,
            Name VARCHAR>,
        Clerk STRUCT<
            Id VARCHAR,
            Name VARCHAR>,
        BasketItems ARRAY< STRUCT<id VARCHAR,
            Name VARCHAR,
            Brand VARCHAR,
            Catergory VARCHAR,
            Price DOUBLE,
            Quantity integer >>) 
WITH (KAFKA_TOPIC='salesbasket',
        VALUE_FORMAT='JSON',
        PARTITIONS=1);
       
       
-- salespayments       
CREATE STREAM salespayments  (
          InvoiceNumber VARCHAR,
          FinTransactionID VARCHAR,
          PayDateTime VARCHAR,
          PayTimestamp TIMESTAMP,
          Paid DOUBLE )        
 WITH (KAFKA_TOPIC='salespayments',
       VALUE_FORMAT='JSON',
       PARTITIONS=1);

don’t know where to even start.