Indexes and Constraints in SYBASE T-SQL

Indexes and Constraints

Indexes: 
2 types of indexes - clustered and nonclustered. Both are B-tree. 
Clustered - only one clustered index per table can exist (data is maintained in clustered index order). 
Nonclustered indexes - you can have 249 of them per table. They maintain pointers to rows (not data pages). 
An index can contain up to 16 columns, but toal index width <= 255.

Creating indexes: 
create unique clustered index name_index  on authors (au_lname, au_fname) 
create index fname_index on authors (au_fname, au_lname) 
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Constraints: 
Primary Key and Unique Constraints 
Check Constraints 
Referential-integrity Constraints 
Primary-Key Constraints 
Foreign-Key Constraints 
Modifying Constraints 
Adding Constraints 
Removing Constraints 
Information on Constraints: 
sp_helpconstraint 
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Comparing Data-integrity Methods: 
Rules, Defaults, Indexes, Constraints, Keys (Primary Key, Foreign Key (primary key from another table), Common key)