fix(duckdb)!: refactor length_sql so it handles any type, not just varchar/blob (#4935)

Author: tekumara

sqlglot/dialects/duckdb.py

@@ -1032,10 +1032,10 @@ def length_sql(self, expression: exp.Length) -> str:
 
             case = (
                 exp.case(self.func("TYPEOF", arg))
-                .when(
-                    "'VARCHAR'", exp.Anonymous(this="LENGTH", expressions=[varchar])
-                )  # anonymous to break length_sql recursion
                 .when("'BLOB'", self.func("OCTET_LENGTH", blob))
+                .else_(
+                    exp.Anonymous(this="LENGTH", expressions=[varchar])
+                )  # anonymous to break length_sql recursion
             )
 
             return self.sql(case)

tests/dialects/test_bigquery.py

@@ -1486,7 +1486,7 @@ def test_bigquery(self):
                 "snowflake": "SELECT LENGTH(foo)",
             },
             write={
-                "duckdb": "SELECT CASE TYPEOF(foo) WHEN 'VARCHAR' THEN LENGTH(CAST(foo AS TEXT)) WHEN 'BLOB' THEN OCTET_LENGTH(CAST(foo AS BLOB)) END",
+                "duckdb": "SELECT CASE TYPEOF(foo) WHEN 'BLOB' THEN OCTET_LENGTH(CAST(foo AS BLOB)) ELSE LENGTH(CAST(foo AS TEXT)) END",
                 "snowflake": "SELECT LENGTH(foo)",
                 "": "SELECT LENGTH(foo)",
             },