Cannot specify more than %d column names for index key list. %d specified.
This error occurs when more than 16 columns are used to create a composite index. A composite index is an index that uses from 2 to 16 columns.
The following example shows a composite index using objects from the pubs database:
create index idxPubNameCity on publishers (pub_name, city) go
Modify the create index statement to use no more than 16 columns. For more information, see the CREATE INDEX statement in the Microsoft SQL Server Transact-SQL Reference.