Re: Different Physical File Attributes.

[rob@xxxxxxxxx]

I really don't know your background so it's hard for me to talk in 
language you'd understand.

If you are familiar with SQL then a table created with a primary key 
constraint will have a "key".  For example
CREATE TABLE RYAN
(MYKEY CHAR ( 5) NOT NULL WITH DEFAULT, 
 MYDATA CHAR ( 15) NOT NULL WITH DEFAULT,
PRIMARY KEY (MYKEY))

With a table set up this way you cannot have two rows in the table with 
the same value for MYKEY.  Also, if you use a HLL language like cobol or 
rpg you could retrieve records by that key using direct language 
attributes.

If you are familiar with DDS it would be more like
                                            UNIQUE
                R RYANR
                  MYKEY          5A
                  MYDATA        15A
                K MYKEY 
The file level keyword UNIQUE says there can only be one row where the 
fields declared keys by the K (as seen in front of MYKEY) are alike.

Now, you could have K fields without UNIQUE.  And instead of being like a 
primary key constraint, it's more like combining a table with an index. 
Understand?

Now, if you do not have any keys, or primary key constraints, then when 
you retrieve rows from the table they are normally retrieved in the order 
they were deposited in the file, or, "arrival sequence".

Rob Berendt