Originally Posted by Mathew_paul
unique key won,t allow null values
are you sure?
Yes, unique constraint don't allow null values.
unique constraint and unique index are different things.
Descriptions of UNIQUE (column-name,...) and PRIMARY KEY (column-name,...)
in TABLE statement in "DB2 SQL Reference" are essentialy same, except...
Only one primary key can be defined on a table.
Another use of PRIMARY KEY is...
REFERENCEStable-name or nickname
The list of column names must match the set of columns (in any
order) of the primary key or a unique constraint that exists on T2
(SQLSTATE 42890). If a column name list is not specified, then T2
must have a primary key (SQLSTATE 42888). Omission of the
column name list is an implicit specification of the columns of that
primary key in the sequence originally specified.