SQL Constraints creation

UNIQUE Constraint

ALTER TABLE [TABLENAME] ADD CONSTRAINT [CONSTRAINTNAME] UNIQUE([COLUMNNAME])

CHECK Constraint

ALTER TABLE [TABLENAME] WITH NOCHECK ADD CONSTRAINT [CONSTRAINTNAME] CHECK  (([COLUMNNAME] IS NOT NULL))

DEFAULT constraint

ALTER TABLE [TABLENAME] ADD CONSTRAINT [CONSTRAINTNAME] DEFAULT (CONVERT([datetime],CONVERT([varchar],getdate(),(101)),(0))) FOR [COLUMNNAME]

NOT NULL constraint

ALTER TABLE [TABLENAME] ALTER COLUMN [COLUMNNAME] <data_type> NOT NULL

FOREIGN KEY constraint

ALTER TABLE [TABLENAME] WITH CHECK ADD CONSTRAINT [CONSTRAINTNAME] FOREIGN KEY([COLUMNNAME])

REFERENCES [PrimaryTableName] ([PKcolumn])

PRIMARY KEY constraint

Specify fields that uniquely identify each record in the table.