Can you give any example how to write a query to count the number of invoices?
Let us see how to write a query to count the number of invoices with practical examples.
Invoice ID is a unique ID or a table column that exists in the Products table.
It is associated with the product information.
One invoice may have multiple products.
See the example below I have used the Current_Products table.
Select * from Current_Products
Invoice_ID ProductID ProductName Sales
1 A Mobile 10000
2 B Desktop 20000
3 C Printer 15000
4 D Headset 2500
5 E Speakers 1300
Using this table I want to count the number of invoices.
For that, I can write a query like this
Select Count(Invoice_ID) from Current_Products
Results would be
Count(Invoice_ID)
5
Remember one thing here Invoice will be generated only when the product is sold.
Let us take the sales invoice detail table here.
Table: Sales_Invoice_Detail
Invoice_Date_ID Invoice_ID Product_ID Quantity Unit_Discuount
1 1 A 1 0
2 1 A 1 0
3 2 B 1 0
Let us say I want to find out the list of all products that have not sold.
For that, I can write this SQL Query.
Select * from Current_Products Where
Product_ID NOT IN (Select distinct Product_ID from Sales_Invoice_Details)
Here output would be
Invoice_ID ProductID ProductName Sales
4 D Headset 2500
5 E Speakers 1300
I hope it is useful.