68  SQL Constraints

68.1 Primary key

68.2 Foreign Key

68.3 Unique

UserId PK Email –

Person PersonKey int TcIdentityNo string unique

68.4 Not null

68.5 Default value

created_at default datetime(‘now’)

68.6 Check (Custom constraints)

Appointments StartDateTime EndDateTime check(EndDateTime > StartDateTime), check(StartDateTime > datetime(‘now’)),

TcIdentityNo, custom function to checksum number Name, custom function to check no punctuation and numbers

Invoice Total check(total > 0)