How to avoid redundant entries in the table-proper table design

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SQL-Server-2008R2

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Hi All
I have a table with the following entries:-

CustName |	CustId |CustomerType|ProdID |ProdName|Units|PurchaseDate
Mr.James Butt	100JSBTM	R	1001	SVS1	5	6/15/2016

Mrs.JosephineDarakjy 101JEDYF	F	1011	SVS1	11	6/15/2016

Mr.ArtVenere	102ATVEM	F	1021	SVV2	4	6/15/2016

Now ProductName has further subtypes with the common group_ProdID and (minor extension to sub product ids).The thing is if a person purchases few subtypes of a specific product,all the customer related entries seems needs to rentered. Any workaround this problem to avoid the repetitive entries)

What I have tried:

 CustName  |	CustId |CustomerType| ProdID    | ProdName|Units |PurchaseDate
Mr.James Butt	    100JSBTM	R	     1001SVST1	 SVS1T1	   5	  6/15/2016
Mr.James Butt	    100JSBTM	R	     1001SVST2	 SVS1T2	   5	  6/15/2016
Mr.James Butt	    100JSBTM	R	     1001SVST3	 SVS1T3	   5	  6/15/2016

Posted 15-Jun-16 0:28am

mousau

Updated 15-Jun-16 2:11am

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CHill60 · Accepted Answer · 2016-06-15T02:11:00

You need to learn about Database Normalisation
The Basics of Database Normalization[^]
1NF, 2NF, 3NF and BCNF in Database Normalization | DBMS Tutorial | Studytonight[^]
Database Normalization Techniques[^]

In this case you could (for example) have tables for Customer, Product and Orders.

SQL

create table Customer
(
	Id int identity(1,1) Primary Key,
	CustId nvarchar(50),
	CustName nvarchar(125),
	CustType char(1)
)
create table Product
(
	Id int identity(1,1) Primary Key,
	ProdID nvarchar(50),
	ProdName nvarchar(125)
)
create table Orders
(
	OrderId int identity(1,1),
	C_Id int, -- Foreign key to Customer Id
	P_Id int, -- Foreign key to Product Id
	Units int,
	PurchaseDate date
)

For the data you included in your example you would have these values

SQL

insert into Customer values ('100JSBTM', 'Mr.James Butt','R')
insert into Product values
('1001SVST1', 'SVS1T1'),
('1001SVST2', 'SVS1T2'),
('1001SVST3', 'SVS1T3')
insert into Orders values
(1,1,5,'2016-6-15'),
(1,2,5,'2016-6-15'),
(1,3,5,'2016-6-15')

And then you would get your results table back using this query

SQL

SELECT CustName, CustId, CustType, ProdID, ProdName, Units, PurchaseDate
FROM Orders O
INNER JOIN Customer C ON O.C_Id = C.Id
INNER JOIN Product P ON O.P_Id = P.Id

Note my example is not optimised - see the links for further ideas