Extract Operation.optimizeDateTime()

h2/src/main/org/h2/expression/Operation.java

@@ -217,6 +217,27 @@ public class Operation extends Expression {
                     dataType = Value.DECIMAL;
                 }
             } else if (DataType.isDateTimeType(l) || DataType.isDateTimeType(r)) {
+                return optimizeDateTime(session, l, r);
+            } else {
+                dataType = Value.getHigherOrder(l, r);
+                if (dataType == Value.ENUM) {
+                    dataType = Value.INT;
+                } else if (DataType.isStringType(dataType) &&
+                        session.getDatabase().getMode().allowPlusForStringConcat) {
+                    opType = OpType.CONCAT;
+                }
+            }
+            break;
+        default:
+            DbException.throwInternalError("type=" + opType);
+        }
+        if (left.isConstant() && (right == null || right.isConstant())) {
+            return ValueExpression.get(getValue(session));
+        }
+        return this;
+    }
+
+    private Expression optimizeDateTime(Session session, int l, int r) {
         switch (opType) {
         case PLUS:
             if (r != Value.getHigherOrder(l, r)) {
@@ -340,23 +361,6 @@ public class Operation extends Expression {
                 DataType.getDataType(l).name + " " +
                 getOperationToken() + " " +
                 DataType.getDataType(r).name);
-            } else {
-                dataType = Value.getHigherOrder(l, r);
-                if (dataType == Value.ENUM) {
-                    dataType = Value.INT;
-                } else if (DataType.isStringType(dataType) &&
-                        session.getDatabase().getMode().allowPlusForStringConcat) {
-                    opType = OpType.CONCAT;
-                }
-            }
-            break;
-        default:
-            DbException.throwInternalError("type=" + opType);
-        }
-        if (left.isConstant() && (right == null || right.isConstant())) {
-            return ValueExpression.get(getValue(session));
-        }
-        return this;
     }
 
     private void swap() {