feat(duckdb)!: Add transpilation support for DATE_DIFF function (#6609)

Author: fivetran-amrutabhimsenayachit

sqlglot/dialects/snowflake.py

@@ -135,7 +135,10 @@ def _build_object_construct(args: t.List) -> t.Union[exp.StarMap, exp.Struct]:
 
 def _build_datediff(args: t.List) -> exp.DateDiff:
     return exp.DateDiff(
-        this=seq_get(args, 2), expression=seq_get(args, 1), unit=map_date_part(seq_get(args, 0))
+        this=seq_get(args, 2),
+        expression=seq_get(args, 1),
+        unit=map_date_part(seq_get(args, 0)),
+        date_part_boundary=True,
     )
 
 

tests/dialects/test_snowflake.py

@@ -2416,6 +2416,45 @@ def test_timestamps(self):
             "DATEDIFF(DAY, CAST('2007-12-25' AS DATE), CAST('2008-12-25' AS DATE))",
         )
 
+        # Test DATEDIFF with WEEK unit - week boundary crossing
+        self.validate_all(
+            "DATEDIFF(WEEK, '2024-12-13', '2024-12-17')",
+            write={
+                "duckdb": "DATE_DIFF('WEEK', DATE_TRUNC('WEEK', CAST('2024-12-13' AS DATE)), DATE_TRUNC('WEEK', CAST('2024-12-17' AS DATE)))",
+                "snowflake": "DATEDIFF(WEEK, '2024-12-13', '2024-12-17')",
+            },
+        )
+        self.validate_all(
+            "DATEDIFF(WEEK, '2024-12-15', '2024-12-16')",
+            write={
+                "duckdb": "DATE_DIFF('WEEK', DATE_TRUNC('WEEK', CAST('2024-12-15' AS DATE)), DATE_TRUNC('WEEK', CAST('2024-12-16' AS DATE)))",
+                "snowflake": "DATEDIFF(WEEK, '2024-12-15', '2024-12-16')",
+            },
+        )
+
+        # Test DATEDIFF with other date parts - should not use DATE_TRUNC
+        self.validate_all(
+            "DATEDIFF(YEAR, '2020-01-15', '2023-06-20')",
+            write={
+                "duckdb": "DATE_DIFF('YEAR', CAST('2020-01-15' AS DATE), CAST('2023-06-20' AS DATE))",
+                "snowflake": "DATEDIFF(YEAR, '2020-01-15', '2023-06-20')",
+            },
+        )
+        self.validate_all(
+            "DATEDIFF(MONTH, '2020-01-15', '2023-06-20')",
+            write={
+                "duckdb": "DATE_DIFF('MONTH', CAST('2020-01-15' AS DATE), CAST('2023-06-20' AS DATE))",
+                "snowflake": "DATEDIFF(MONTH, '2020-01-15', '2023-06-20')",
+            },
+        )
+        self.validate_all(
+            "DATEDIFF(QUARTER, '2020-01-15', '2023-06-20')",
+            write={
+                "duckdb": "DATE_DIFF('QUARTER', CAST('2020-01-15' AS DATE), CAST('2023-06-20' AS DATE))",
+                "snowflake": "DATEDIFF(QUARTER, '2020-01-15', '2023-06-20')",
+            },
+        )
+
         self.validate_identity("DATEADD(y, 5, x)", "DATEADD(YEAR, 5, x)")
         self.validate_identity("DATEADD(y, 5, x)", "DATEADD(YEAR, 5, x)")
         self.validate_identity("DATE_PART(yyy, x)", "DATE_PART(YEAR, x)")