diff --git a/x-pack/plugin/sql/qa/src/main/resources/null.csv-spec b/x-pack/plugin/sql/qa/src/main/resources/null.csv-spec
index 19541cf5d9f32..610217b233314 100644
--- a/x-pack/plugin/sql/qa/src/main/resources/null.csv-spec
+++ b/x-pack/plugin/sql/qa/src/main/resources/null.csv-spec
@@ -61,6 +61,13 @@ c:i
 ;
 
 coalesceMixed
+SELECT COALESCE(null, 123, null, 321);
+
+COALESCE(null, 123, null, 321):i
+123
+;
+
+coalesceMixedWithAlias
 SELECT COALESCE(null, 123, null, 321) AS c;
 
 c:i
diff --git a/x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/expression/predicate/conditional/ConditionalFunction.java b/x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/expression/predicate/conditional/ConditionalFunction.java
index 3de85185e8a4f..b3841f09e825e 100644
--- a/x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/expression/predicate/conditional/ConditionalFunction.java
+++ b/x-pack/plugin/sql/src/main/java/org/elasticsearch/xpack/sql/expression/predicate/conditional/ConditionalFunction.java
@@ -25,7 +25,7 @@
  */
 public abstract class ConditionalFunction extends ScalarFunction {
 
-    protected DataType dataType = DataType.NULL;
+    protected DataType dataType = null;
 
     ConditionalFunction(Source source, List<Expression> fields) {
         super(source, fields);
@@ -33,6 +33,12 @@ public abstract class ConditionalFunction extends ScalarFunction {
 
     @Override
     public DataType dataType() {
+        if (dataType == null) {
+            dataType = DataType.NULL;
+            for (Expression exp : children()) {
+                dataType = DataTypeConversion.commonType(dataType, exp.dataType());
+            }
+        }
         return dataType;
     }
 
@@ -61,7 +67,6 @@ protected TypeResolution resolveType() {
                         child.dataType().typeName));
                 }
             }
-            dataType = DataTypeConversion.commonType(dataType, child.dataType());
         }
         return TypeResolution.TYPE_RESOLVED;
     }
diff --git a/x-pack/plugin/sql/src/test/java/org/elasticsearch/xpack/sql/optimizer/OptimizerTests.java b/x-pack/plugin/sql/src/test/java/org/elasticsearch/xpack/sql/optimizer/OptimizerTests.java
index a23d88b595630..2506e3df70220 100644
--- a/x-pack/plugin/sql/src/test/java/org/elasticsearch/xpack/sql/optimizer/OptimizerTests.java
+++ b/x-pack/plugin/sql/src/test/java/org/elasticsearch/xpack/sql/optimizer/OptimizerTests.java
@@ -498,6 +498,7 @@ public void testSimplifyCoalesceRandomNullsWithValue() {
                         randomListOfNulls())));
         assertEquals(1, e.children().size());
         assertEquals(TRUE, e.children().get(0));
+        assertEquals(DataType.BOOLEAN, e.dataType());
     }
 
     private List<Expression> randomListOfNulls() {
@@ -511,6 +512,7 @@ public void testSimplifyCoalesceFirstLiteral() {
         assertEquals(Coalesce.class, e.getClass());
         assertEquals(1, e.children().size());
         assertEquals(TRUE, e.children().get(0));
+        assertEquals(DataType.BOOLEAN, e.dataType());
     }
 
     public void testSimplifyIfNullNulls() {
@@ -524,11 +526,13 @@ public void testSimplifyIfNullWithNullAndValue() {
         assertEquals(IfNull.class, e.getClass());
         assertEquals(1, e.children().size());
         assertEquals(ONE, e.children().get(0));
+        assertEquals(DataType.INTEGER, e.dataType());
 
         e = new SimplifyConditional().rule(new IfNull(EMPTY, ONE, NULL));
         assertEquals(IfNull.class, e.getClass());
         assertEquals(1, e.children().size());
         assertEquals(ONE, e.children().get(0));
+        assertEquals(DataType.INTEGER, e.dataType());
     }
 
     public void testFoldNullNotAppliedOnNullIf() {
@@ -556,6 +560,7 @@ public void testSimplifyGreatestRandomNullsWithValue() {
         assertEquals(2, e.children().size());
         assertEquals(ONE, e.children().get(0));
         assertEquals(TWO, e.children().get(1));
+        assertEquals(DataType.INTEGER, e.dataType());
     }
 
     public void testSimplifyLeastNulls() {
@@ -577,6 +582,7 @@ public void testSimplifyLeastRandomNullsWithValue() {
         assertEquals(2, e.children().size());
         assertEquals(ONE, e.children().get(0));
         assertEquals(TWO, e.children().get(1));
+        assertEquals(DataType.INTEGER, e.dataType());
     }
     
     public void testConcatFoldingIsNotNull() {