Merging two SQL tables - sql

Question

I have a table called Store Sales with the following columns
Date
Total Qty Sold
RRP
Total Value Sold
Branch No.
Barcodes
Unit Cost
Then I have another table called ESales that contains this
Inv Date
Our Ship Qty
Unit Price (RRP Inc VAT)
Line Total
Invoice
Order
Line
Brand
Part
Description
Our Order Qty
Unit Price (Exc VAT)
Discount %
Discount Amt (Inc VAT)
Discount Amount (Exc VAT)
Tax Category
Tax Exempt
Group
Sales Cat
Cust. ID
Title
Customer
Name
Tax ID
Rep. ID
Credit Memo
Unit Price
Amount
Category ID
Cust. Amount
Number01
ShortChar01
ShortChar02
Clubcard
There are matching fields but none with the same name. They are
Inv Date = Date
Our Ship Qty = Total Qty Sold
Unit Price (RRP Inc VAT) = RRP
Line Total = Total Value Sold
What I want to do in merge the values in StoreSales to ESales and create additional columns for the data that is not there, these are
Branch No
Barcodes
Unit Cost
Any ideas how to insert the matching values and create the three new ones?

Answer 1

Instead of creating a new table, I would just start with a query that shows you all the data you are describing. The way you merge data from multiple tables together is by using a JOIN command. Here is a example query that shows everything from the ESales table and the additional columns from the StoreSales table you described:
SELECT e.*, s.[Branch No], s.[Barcodes], s.[Unit Cost]
FROM StoreSales s
INNER JOIN ESales e ON
e.[Inv Date] = s.[Date] AND
e.[Our Ship Qty] = s.[Total Qty Sold] AND
e.[Unit Price (RRP Inc VAT)] = s.[RRP] AND
e.[Line Total] = s.[Total Value Sold]
Once you get a query you like, you can save it as a VIEW which essentially lets you interact with the result of this query as if it were a separate table.
I will caution you that you have to be very careful doing this. Usually, data will have some kind of common field like a Order ID or a product SKU that makes it very clear what unique item you are referencing in the database. Joining by things like date, order total, price, etc is bad practice. This is because there is no way to guarantee that there aren't two orders with the same date or the same order total. Those things are not unique to any one particular order.