[SPARK-17117][SQL] 1 / NULL should not fail analysis

## What changes were proposed in this pull request?
This patch fixes the problem described in SPARK-17117, i.e. "SELECT 1 / NULL" throws an analysis exception:

```
org.apache.spark.sql.AnalysisException: cannot resolve '(1 / NULL)' due to data type mismatch: differing types in '(1 / NULL)' (int and null).
```

The problem is that division type coercion did not take null type into account.

## How was this patch tested?
A unit test for the type coercion, and a few end-to-end test cases using SQLQueryTestSuite.

Author: petermaxlee <petermaxlee@gmail.com>

Closes #14695 from petermaxlee/SPARK-17117.

1 files changed, 8 insertions, 1 deletions

diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/TypeCoercionSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/TypeCoercionSuite.scala
index a13c45fe2f..9560563a8c 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/TypeCoercionSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/TypeCoercionSuite.scala
@@ -19,7 +19,7 @@ package org.apache.spark.sql.catalyst.analysis
 
 import java.sql.Timestamp
 
-import org.apache.spark.sql.catalyst.analysis.TypeCoercion.{Division, FunctionArgumentConversion}
+import org.apache.spark.sql.catalyst.analysis.TypeCoercion._
 import org.apache.spark.sql.catalyst.dsl.expressions._
 import org.apache.spark.sql.catalyst.expressions._
 import org.apache.spark.sql.catalyst.plans.PlanTest
@@ -730,6 +730,13 @@ class TypeCoercionSuite extends PlanTest {
     // the right expression to Decimal.
     ruleTest(rules, sum(Divide(Decimal(4.0), 3)), sum(Divide(Decimal(4.0), 3)))
   }
+
+  test("SPARK-17117 null type coercion in divide") {
+    val rules = Seq(FunctionArgumentConversion, Division, ImplicitTypeCasts)
+    val nullLit = Literal.create(null, NullType)
+    ruleTest(rules, Divide(1L, nullLit), Divide(Cast(1L, DoubleType), Cast(nullLit, DoubleType)))
+    ruleTest(rules, Divide(nullLit, 1L), Divide(Cast(nullLit, DoubleType), Cast(1L, DoubleType)))
+  }
 }