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Sybase » DDL » Design »

Creating a constraint


Contraints are used to define primary keys, enforce uniqueness, and to describe
foreign key relationships. Note that unique or primary key constraints
create indexes upon creation.

/* primary key for the employee table */
alter table employee add constraint
emp_constr primary key(emp_id)
/* add unique requirement for invoice table */
alter table invoice add constraint
inv_constr unique nonclustered(cust_id,inv_date)
/* add foreign key for relationship between invoice and employee */
alter table invoice add constraint inv_fk_emp
foreign key (sales_rep_id)
references employee(emp_id)

Sybase : Related Topics

Sybase : DDL : Sybase data types
Sybase : DDL : Creating a table
Sybase : DDL : Altering a table
Sybase : DDL : Creating an index
Sybase : DDL : Clustered vs non-clustered indexes
Sybase : DDL : Table Partitioning
Sybase : DDL : Modifying a Colunm
Sybase : DDL : Alter a column

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