fix(snowflake)!: support TO_CHAR to duckdb STRFTIME (tobymao#4866)

* fix(snowflake): support TO_CHAR to duckdb STRFTIME

* PR feedback 1

Author: geooo109

sqlglot/dialects/dialect.py

@@ -1856,3 +1856,17 @@ def groupconcat_sql(
             listagg.set("expressions", [f"{args}{self.sql(expression=expression.this)}"])
 
     return self.sql(listagg)
+
+
+def build_timetostr_or_tochar(args: t.List, dialect: Dialect) -> exp.TimeToStr | exp.ToChar:
+    this = seq_get(args, 0)
+
+    if this and not this.type:
+        from sqlglot.optimizer.annotate_types import annotate_types
+
+        annotate_types(this)
+        if this.is_type(*exp.DataType.TEMPORAL_TYPES):
+            dialect_name = dialect.__class__.__name__.lower()
+            return build_formatted_time(exp.TimeToStr, dialect_name, default=True)(args)
+
+    return exp.ToChar.from_arg_list(args)

sqlglot/dialects/oracle.py

@@ -6,6 +6,7 @@
 from sqlglot.dialects.dialect import (
     Dialect,
     NormalizationStrategy,
+    build_timetostr_or_tochar,
     build_formatted_time,
     no_ilike_sql,
     rename_func,
@@ -21,19 +22,6 @@
     from sqlglot._typing import E
 
 
-def _build_timetostr_or_tochar(args: t.List) -> exp.TimeToStr | exp.ToChar:
-    this = seq_get(args, 0)
-
-    if this and not this.type:
-        from sqlglot.optimizer.annotate_types import annotate_types
-
-        annotate_types(this)
-        if this.is_type(*exp.DataType.TEMPORAL_TYPES):
-            return build_formatted_time(exp.TimeToStr, "oracle", default=True)(args)
-
-    return exp.ToChar.from_arg_list(args)
-
-
 def _trim_sql(self: Oracle.Generator, expression: exp.Trim) -> str:
     position = expression.args.get("position")
 
@@ -117,7 +105,7 @@ class Parser(parser.Parser):
             **parser.Parser.FUNCTIONS,
             "NVL": lambda args: build_coalesce(args, is_nvl=True),
             "SQUARE": lambda args: exp.Pow(this=seq_get(args, 0), expression=exp.Literal.number(2)),
-            "TO_CHAR": _build_timetostr_or_tochar,
+            "TO_CHAR": build_timetostr_or_tochar,
             "TO_TIMESTAMP": build_formatted_time(exp.StrToTime, "oracle"),
             "TO_DATE": build_formatted_time(exp.StrToDate, "oracle"),
             "TRUNC": lambda args: exp.DateTrunc(

sqlglot/dialects/snowflake.py

@@ -6,6 +6,7 @@
 from sqlglot.dialects.dialect import (
     Dialect,
     NormalizationStrategy,
+    build_timetostr_or_tochar,
     binary_from_function,
     build_default_decimal_type,
     build_timestamp_from_parts,
@@ -463,6 +464,7 @@ class Parser(parser.Parser):
             "TRY_TO_TIMESTAMP": _build_datetime(
                 "TRY_TO_TIMESTAMP", exp.DataType.Type.TIMESTAMP, safe=True
             ),
+            "TO_CHAR": build_timetostr_or_tochar,
             "TO_DATE": _build_datetime("TO_DATE", exp.DataType.Type.DATE),
             "TO_NUMBER": lambda args: exp.ToNumber(
                 this=seq_get(args, 0),

tests/dialects/test_snowflake.py

@@ -588,6 +588,16 @@ def test_snowflake(self):
                 "teradata": "TO_CHAR(x, y)",
             },
         )
+        self.validate_identity(
+            "TO_CHAR(foo::DATE, 'yyyy')", "TO_CHAR(CAST(CAST(foo AS DATE) AS TIMESTAMP), 'yyyy')"
+        )
+        self.validate_all(
+            "TO_CHAR(foo::TIMESTAMP, 'YYYY-MM')",
+            write={
+                "snowflake": "TO_CHAR(CAST(foo AS TIMESTAMP), 'yyyy-mm')",
+                "duckdb": "STRFTIME(CAST(foo AS TIMESTAMP), '%Y-%m')",
+            },
+        )
         self.validate_all(
             "SQUARE(x)",
             write={