Fix(snowflake): handle DIV0 case where divident is null (#3975)

Author: georgesittas

sqlglot/dialects/snowflake.py

@@ -93,7 +93,9 @@ def _builder(args: t.List) -> E:
 
 # https://docs.snowflake.com/en/sql-reference/functions/div0
 def _build_if_from_div0(args: t.List) -> exp.If:
-    cond = exp.EQ(this=seq_get(args, 1), expression=exp.Literal.number(0))
+    cond = exp.EQ(this=seq_get(args, 1), expression=exp.Literal.number(0)).and_(
+        exp.Is(this=seq_get(args, 0), expression=exp.null()).not_()
+    )
     true = exp.Literal.number(0)
     false = exp.Div(this=seq_get(args, 0), expression=seq_get(args, 1))
     return exp.If(this=cond, true=true, false=false)

tests/dialects/test_snowflake.py

@@ -598,12 +598,12 @@ def test_snowflake(self):
         self.validate_all(
             "DIV0(foo, bar)",
             write={
-                "snowflake": "IFF(bar = 0, 0, foo / bar)",
-                "sqlite": "IIF(bar = 0, 0, CAST(foo AS REAL) / bar)",
-                "presto": "IF(bar = 0, 0, CAST(foo AS DOUBLE) / bar)",
-                "spark": "IF(bar = 0, 0, foo / bar)",
-                "hive": "IF(bar = 0, 0, foo / bar)",
-                "duckdb": "CASE WHEN bar = 0 THEN 0 ELSE foo / bar END",
+                "snowflake": "IFF(bar = 0 AND NOT foo IS NULL, 0, foo / bar)",
+                "sqlite": "IIF(bar = 0 AND NOT foo IS NULL, 0, CAST(foo AS REAL) / bar)",
+                "presto": "IF(bar = 0 AND NOT foo IS NULL, 0, CAST(foo AS DOUBLE) / bar)",
+                "spark": "IF(bar = 0 AND NOT foo IS NULL, 0, foo / bar)",
+                "hive": "IF(bar = 0 AND NOT foo IS NULL, 0, foo / bar)",
+                "duckdb": "CASE WHEN bar = 0 AND NOT foo IS NULL THEN 0 ELSE foo / bar END",
             },
         )
         self.validate_all(