How do I structure a Database with a Sales Table MySql - mysql

Question

I have a sales table that I want to record all the sales done by the employee.
The problem i'm having is that I can only store one ProductId that comes from a Products table. What is wrong is that a sale has multiples products and with my current structure I can only store one ProductId. I know my approach is wrong but I just don't know how to properly fix it. The question I have is how do I store multiples products in the Sales Table.
This is my Sales Table columns.
CREATE TABLE `Sales` (
`SaleId` int(11) unsigned NOT NULL AUTO_INCREMENT,
`EmployeeId` int(11) unsigned NOT NULL,
`ProductId` int(11) unsigned NOT NULL,
PRIMARY KEY (`SaleId`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

Answer 1

Your table and approach is ok.
You just have to insert one row in your sales table per product-id.
The unique key for the sales is the SaleId,
the foreign keys for Employee and Product are also there.
The only thing that's missing in your table is the sale quantity and amount.
It's the typical n:m-issue which is solved by the V-structure.

Answer 2

You need a second table, a Sales-Product table:
CREATE TABLE `SaleProduct` (
`SaleId` int(11) unsigned NOT NULL,
`ProductId` int(11) unsigned NOT NULL,
`Quantity` int(11) unsigned NOT NULL,
PRIMARY KEY (`SaleId`, `ProductId`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
and change your Sales Table:
CREATE TABLE `Sales` (
`SaleId` int(11) unsigned NOT NULL AUTO_INCREMENT,
`EmployeeId` int(11) unsigned NOT NULL,
PRIMARY KEY (`SaleId`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

Answer 3

The second way I suggest is more "standard" but since I have no idea how do you query the table and the size of it, the first method might(?) be useful
concatenate all prod_id into a single string, get them using regexp
example: prod_id = 13_07_255_23_11
SELECT * FROM Sales WHERE ProductId REGEXP '(^|)23(|$)';
split a single sale into multiple entries, have sales_id and product_id be your combined unique/primary key