feat(snowflake): Support for inline FOREIGN KEY (#4493)

* feat(snowflake): Support for inline FOREIGN KEY

* Update sqlglot/dialects/snowflake.py

---------

Co-authored-by: Jo <[email protected]>

Author: VaggelisD

sqlglot/dialects/snowflake.py

@@ -799,6 +799,14 @@ def _parse_lambda_arg(self) -> t.Optional[exp.Expression]:
 
             return this
 
+        def _parse_foreign_key(self) -> exp.ForeignKey:
+            # inlineFK, the REFERENCES columns are implied
+            if self._match(TokenType.REFERENCES, advance=False):
+                return self.expression(exp.ForeignKey)
+
+            # outoflineFK, explicitly names the columns
+            return super()._parse_foreign_key()
+
     class Tokenizer(tokens.Tokenizer):
         STRING_ESCAPES = ["\\", "'"]
         HEX_STRINGS = [("x'", "'"), ("X'", "'")]

sqlglot/expressions.py

@@ -2113,7 +2113,7 @@ class Directory(Expression):
 
 class ForeignKey(Expression):
     arg_types = {
-        "expressions": True,
+        "expressions": False,
         "reference": False,
         "delete": False,
         "update": False,

sqlglot/generator.py

@@ -2829,13 +2829,14 @@ def check_sql(self, expression: exp.Check) -> str:
 
     def foreignkey_sql(self, expression: exp.ForeignKey) -> str:
         expressions = self.expressions(expression, flat=True)
+        expressions = f" ({expressions})" if expressions else ""
         reference = self.sql(expression, "reference")
         reference = f" {reference}" if reference else ""
         delete = self.sql(expression, "delete")
         delete = f" ON DELETE {delete}" if delete else ""
         update = self.sql(expression, "update")
         update = f" ON UPDATE {update}" if update else ""
-        return f"FOREIGN KEY ({expressions}){reference}{delete}{update}"
+        return f"FOREIGN KEY{expressions}{reference}{delete}{update}"
 
     def primarykey_sql(self, expression: exp.ForeignKey) -> str:
         expressions = self.expressions(expression, flat=True)

tests/dialects/test_snowflake.py

@@ -1456,6 +1456,9 @@ def test_ddl(self):
         self.validate_identity(
             """CREATE OR REPLACE FUNCTION ibis_udfs.public.object_values("obj" OBJECT) RETURNS ARRAY LANGUAGE JAVASCRIPT STRICT AS ' return Object.values(obj) '"""
         )
+        self.validate_identity(
+            "CREATE OR REPLACE TABLE TEST (SOME_REF DECIMAL(38, 0) NOT NULL FOREIGN KEY REFERENCES SOME_OTHER_TABLE (ID))"
+        )
         self.validate_identity(
             "CREATE OR REPLACE FUNCTION my_udf(location OBJECT(city VARCHAR, zipcode DECIMAL(38, 0), val ARRAY(BOOLEAN))) RETURNS VARCHAR AS $$ SELECT 'foo' $$",
             "CREATE OR REPLACE FUNCTION my_udf(location OBJECT(city VARCHAR, zipcode DECIMAL(38, 0), val ARRAY(BOOLEAN))) RETURNS VARCHAR AS ' SELECT \\'foo\\' '",