fix aggregate scale for temporal type bug

src/sql/engine/expr/ob_expr_ifnull.cpp

@@ -68,9 +68,9 @@ int ObExprIfNull::calc_result_type2(
       type.set_accuracy(ObAccuracy::DDL_DEFAULT_ACCURACY[ObIntType].get_accuracy());
     }
 
-    // set scale
-    ObScale scale1 = type1.get_scale();
-    ObScale scale2 = type2.get_scale();
+    //set scale
+    ObScale scale1 = type1.is_null() ? 0 : type1.get_scale();
+    ObScale scale2 = type2.is_null() ? 0 : type2.get_scale();
     if (-1 != scale1 && -1 != scale2) {
       type.set_scale(static_cast<ObScale>(max(scale1, scale2)));
     } else {

src/sql/engine/expr/ob_expr_nvl.cpp

@@ -98,8 +98,8 @@ int ObExprNvl::calc_result_type2(
     } else {
       type.set_accuracy(type2.get_accuracy());
     }
-    ObScale scale1 = type1.get_scale();
-    ObScale scale2 = type2.get_scale();
+    ObScale scale1 = type1.is_null() ? 0 : type1.get_scale();
+    ObScale scale2 = type2.is_null() ? 0 : type2.get_scale();
     if (-1 != scale1 && -1 != scale2) {
       type.set_scale(static_cast<ObScale>(max(scale1, scale2)));
     } else {

src/sql/engine/expr/ob_expr_operator.cpp

@@ -1127,8 +1127,7 @@ int ObExprOperator::aggregate_temporal_accuracy_for_merge(
       }
     }
     if (OB_UNLIKELY(scale < 0)) {
-      ret = OB_ERR_UNEXPECTED;
-      LOG_WARN("unexpected scale.", K(ret), K(scale));
+      type.set_scale(ObAccuracy::MAX_ACCURACY2[is_oracle_mode()][type.get_type()].get_scale());
     } else {
       type.set_scale(scale);
     }