Every source table must contain an IDENTITY column to uniquely identify each row and provide a means of joining the index table and the source table. When you create a text index, the IDENTITY column is passed with the indexed columns to the Full-Text Search engine. The IDENTITY column value is stored in the text index and is mapped to the id column in the index table.
For example, to create an IDENTITY column in a table named composers, define the table as follows:
create table composers ( id numeric(m,n) identity, comp_fname char(30) not null, comp_lname char(30) not null, text_col text )
where m =< 38 and n always = 0
To add an IDENTITY column to an existing table, enter:
alter table table_name add id numeric(10,0) identity