topic Re: Unique key in Application Development and Automation Discussions

Unique key

Former Member — Fri, 10 Nov 2006 10:42:01 GMT

Hi Experts,

What is the difference between a Primary key and Unique in ABAP?

Regards

Re: Unique key

Former Member — Fri, 10 Nov 2006 10:45:55 GMT

The primary key is the key obtained by all key fields, an unique key is a key created by several fields (they can be or not be key fields) and the key has to be unique.

So the primary key is always unique key a secondary index could be unique, but generally it isn't.

Max

Re: Unique key

anversha_s — Fri, 10 Nov 2006 10:46:06 GMT

1. This concept of primary key and unique key

comes into picture at the database level

(especially oracle)

2. The only difference is that

unique key allows

insertion of a NULL value

into the key field(s)

Where as primary key does not allow.

3. Similary is ;

Both maintain unique/distinct values

in the table.

I hope it helps.

regards,

Anver

Re: Unique key

Former Member — Fri, 10 Nov 2006 10:47:20 GMT

Hi Ravi,

Primary Key = Not Null + Unique(You cannot store empty or null values into Primary key)

Unique Key = You can store one empty value along with other unique values.

Simply, if your field is Primary key , you cannot insert a duplicate or a empty value into it.

But if it is unique then you can inser one empty value but it should not be duplicate.

Regards,

Raghav

Re: Unique key

Former Member — Fri, 10 Nov 2006 10:58:29 GMT

Hi All,

Thanks.