FOREIGN KEY

Description

SnowFlake supports the grammar for Referential Integrity Constraints, and their properties to facilitate the migration from other databases.

Syntax in SQL Server

FOREIGN KEY   
        ( column [ ,...n ] )  
        REFERENCES referenced_table_name [ ( ref_column [ ,...n ] ) ]   
        [ ON DELETE { NO ACTION | CASCADE | SET NULL | SET DEFAULT } ]   
        [ ON UPDATE { NO ACTION | CASCADE | SET NULL | SET DEFAULT } ]   
        [ NOT FOR REPLICATION ]

Syntax in Snowflake

  [ FOREIGN KEY ]
  REFERENCES <ref_table_name> [ ( <ref_col_name> ) ]
  [ MATCH { FULL | SIMPLE | PARTIAL } ]
  [ ON [ UPDATE { CASCADE | SET NULL | SET DEFAULT | RESTRICT | NO ACTION } ]
       [ DELETE { CASCADE | SET NULL | SET DEFAULT | RESTRICT | NO ACTION } ] ]
  [ [ NOT ] ENFORCED ]
  [ [ NOT ] DEFERRABLE ]
  [ INITIALLY { DEFERRED | IMMEDIATE } ]
  [ ENABLE | DISABLE ]
  [ VALIDATE | NOVALIDATE ]
  [ RELY | NORELY ]

Sample Source Patterns

SQL Server

ALTER TABLE [Tests].[dbo].[Employee]
ADD CONSTRAINT FK_Department FOREIGN KEY(DepartmentID) REFERENCES Department(DepartmentID) 
ON UPDATE CASCADE
ON DELETE NO ACTION
NOT FOR REPLICATION;

Snowflake

ALTER TABLE IF EXISTS Tests.dbo.Employee
ADD CONSTRAINT FK_Department FOREIGN KEY(DepartmentID) REFERENCES PUBLIC.Department (DepartmentID)
ON UPDATE CASCADE
ON DELETE NO ACTION
-- ** MSC-WARNING - MSCEWI1042 - Commented NOT FOR REPLICATION - THIS IS NON-RELEVANT **
--NOT FOR REPLICATION
                   ;

Constraints are not enforced in Snowflake, excepting NOT NULL.

Primary and Foreign Key are only used for documentation purposes more than design constraints.

Known Issues

No issues were found

Related EWIs

1. MSCEWI1042: Non-relevant syntax