Best structure for inventory database

Question

I want to create a small database for my inventory but I have some problems on picking a structure. The inventory will be updated daily at the end of the day.

The problem I am facing is the following.

I have a table for my products, having an

id, name, price, quantity. 

Now I have another table for my sales, but there is my problem. What kind of fields do I need to have. At the end of the day I want to store a record like this:

20       product_x       $ 5,00         $ 100,- 20       product_y       $ 5,00         $ 100,- 20       product_z       $ 5,00         $ 100,- 20       product_a       $ 5,00         $ 100,- -------------------------------------------------                                         $ 400,- 

So how do I model this in a sales record. Do I just create a concatenated record with the product id's comma separated.

Or is there another way do model this the right way.

Answer 1

This is a model which supports many aspects,

1. Supports Sites, Locations and Warehouses etc.
2. Supports Categorization and Grouping
3. Support Generic Product (Ex. "Table Clock" and specific product "Citizen C123 Multi Alarm Clock" )
4. Also support Brand Variants (by various manufacturers)
5. Has CSM (color / size / model support) Ex. Bata Sandles (Color 45 Inch Blue color)
6. Product Instances with serials (such as TVs , Refrigerators etc.)
7. Lot control / Batch control with serial numbers.
8. Pack Size / UOM and UOM Conversion
9. Manufacturer and Brands as well as Suppliers
10. Also included example transaction table (Purchase order)
11. There are many other transaction types such as Issues, Transfers, Adjustments etc.

Hope this would help. Please let me know if you need further information on each table.

Cheers...!!!

Wajira Weerasinghe.

Sites

• id
• site_code
• Site_name

Warehouse

• id
• site_id
• warehouse_code
• warehouse_name

Item Category

• id
• category_code
• category_name

Item Group

• id
• group_code
• group_name

Generic Product

• id
• generic_name

Product

• id
• product_code
• category_id
• group_id
• brand_id
• generic_id
• model_id/part_id
• product_name
• product_description
• product_price (current rate)
• has_instances(y/n)
• has_lots (y/n)
• has_attributes
• default_uom
• pack_size
• average_cost
• single_unit_product_code (for packs)
• dimension_group (pointing to dimensions)
• lot_information
• warranty_terms (general not specific)
• is_active
• deleted

product attribute type (color/size etc.)

• id
• attribute_name

product_attribute

• id
• product_id
• attribute_id

product attribute value (this product -> red)

• id
• product_attribute_id
• value

product_instance

• id
• product_id
• instance_name (as given by manufacturer)
• serial_number
• brand_id (is this brand)
• stock_id (stock record pointing qih, location etc.)
• lot_information (lot_id)
• warranty_terms
• product attribute value id (if applicable)

product lot

• id
• lot_code/batch_code
• date_manufactured
• date_expiry
• product attribute value id (if applicable)

Brand

• id
• manufacturer_id
• brand_code
• brand_name

Brand Manufacturer

• id
• manufacturer_name

Stock

• id
• product_id
• warehouse_id, zone_id, level_id, rack_id etc.
• quantity in hand
• product attribute value id (if applicable) [we have 4 red color items etc.]

Product Price Records

• product_id
• from_date
• product_price

Purchase Order Header

• id
• supplier_id
• purchase_date
• total_amount

Purchase Order Line

• id
• po_id
• product_id
• unit_price
• quantity

Supplier

• id
• supplier_code
• supplier_name
• supplier_type

product_uom

• id
• uom_name

product_uom_conversion

• id
• from_uom_id
• to_uom_id
• conversion_rule

Answer 2

I'd have a table with a row per item per day - store the date, the item ID, the quantity sold, and the price sold at (store this even though it's also in the product table - if that changes, you want the value you actually sold at preserved). You can compute totals per item-day and totals per day in queries.

Tables:

create table product (   id integer primary key,   name varchar(100) not null,   price decimal(6,2) not null,   inventory integer not null );  create table sale (   saledate date not null,   product_id integer not null references product,   quantity integer not null,   price decimal(6,2) not null,   primary key (saledate, product_id) ); 

Reporting on a day:

select s.product_id, p.name, s.quantity, s.price, (s.quantity * s.price) as total from product p, sale s where p.id = s.product_id and s.saledate = date '2010-12-5'; 

Reporting on all days:

select saledate, sum(quantity * price) as total from sale group by saledate order by saledate; 

A nice master report over all days, with a summary line:

select * from (     (select s.saledate, s.product_id, p.name, s.quantity, s.price, (s.quantity * s.price) as total     from product p, sale s     where p.id = s.product_id)   union     (select saledate, NULL, 'TOTAL', sum(quantity), NULL, sum(quantity * price) as total     from sale group by saledate) ) as summedsales order by saledate, product_id;