From b5ae01f1eb64ae7a54a3c66b1528aa910659bb4c Mon Sep 17 00:00:00 2001
From: HangyuanLiu <460660596@qq.com>
Date: Fri, 20 Sep 2019 16:16:56 +0800
Subject: [PATCH] fix two digit year bug in to_days function

---
 .../apache/doris/analysis/DateLiteral.java    | 24 +++++++-
 .../doris/analysis/DateLiteralTest.java       | 58 +++++++++++++++++++
 2 files changed, 80 insertions(+), 2 deletions(-)
 create mode 100644 fe/src/test/java/org/apache/doris/analysis/DateLiteralTest.java

diff --git a/fe/src/main/java/org/apache/doris/analysis/DateLiteral.java b/fe/src/main/java/org/apache/doris/analysis/DateLiteral.java
index eafcd190b7b896..9aefc093c376ef 100644
--- a/fe/src/main/java/org/apache/doris/analysis/DateLiteral.java
+++ b/fe/src/main/java/org/apache/doris/analysis/DateLiteral.java
@@ -56,10 +56,21 @@ public class DateLiteral extends LiteralExpr {
     
     private static DateTimeFormatter DATE_TIME_FORMATTER = null;
     private static DateTimeFormatter DATE_FORMATTER = null;
+    /* 
+     * Dates containing two-digit year values are ambiguous because the century is unknown. 
+     * MySQL interprets two-digit year values using these rules:
+     * Year values in the range 70-99 are converted to 1970-1999.
+     * Year values in the range 00-69 are converted to 2000-2069.
+     * */
+    private static DateTimeFormatter DATE_TIME_FORMATTER_TWO_DIGIT = null;
+    private static DateTimeFormatter DATE_FORMATTER_TWO_DIGIT = null;
+
     static {
         try {
             DATE_TIME_FORMATTER = formatBuilder("%Y-%m-%d %H:%i:%s").toFormatter();
             DATE_FORMATTER = formatBuilder("%Y-%m-%d").toFormatter();
+            DATE_TIME_FORMATTER_TWO_DIGIT = formatBuilder("%y-%m-%d %H:%i:%s").toFormatter();
+            DATE_FORMATTER_TWO_DIGIT = formatBuilder("%y-%m-%d").toFormatter();
         } catch (AnalysisException e) {
             LOG.error("invalid date format", e);
             System.exit(-1);
@@ -171,10 +182,19 @@ private void init(String s, Type type) throws AnalysisException {
             Preconditions.checkArgument(type.isDateType());
             LocalDateTime dateTime;
             if (type == Type.DATE) {
-                dateTime = DATE_FORMATTER.parseLocalDateTime(s);
+                if (s.split("-")[0].length() == 2) {
+                    dateTime = DATE_FORMATTER_TWO_DIGIT.parseLocalDateTime(s);
+                } else {
+                    dateTime = DATE_FORMATTER.parseLocalDateTime(s);
+                }
             } else {
-                dateTime = DATE_TIME_FORMATTER.parseLocalDateTime(s);
+                if (s.split("-")[0].length() == 2) {
+                    dateTime = DATE_TIME_FORMATTER_TWO_DIGIT.parseLocalDateTime(s);
+                } else {
+                    dateTime = DATE_TIME_FORMATTER.parseLocalDateTime(s);
+                }
             }
+
             year = dateTime.getYear();
             month = dateTime.getMonthOfYear();
             day = dateTime.getDayOfMonth();
diff --git a/fe/src/test/java/org/apache/doris/analysis/DateLiteralTest.java b/fe/src/test/java/org/apache/doris/analysis/DateLiteralTest.java
new file mode 100644
index 00000000000000..21211315896176
--- /dev/null
+++ b/fe/src/test/java/org/apache/doris/analysis/DateLiteralTest.java
@@ -0,0 +1,58 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package org.apache.doris.analysis;
+
+import org.apache.doris.catalog.Type;
+import org.apache.doris.common.AnalysisException;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class DateLiteralTest {
+
+    @Test
+    public void TwoDigitYear() {
+        boolean hasException = false;
+        try {
+            DateLiteral literal = new DateLiteral("1997-10-07", Type.DATE);
+            Assert.assertEquals(1997, literal.getYear());
+
+            DateLiteral literal2 = new DateLiteral("97-10-07", Type.DATE);
+            Assert.assertEquals(1997, literal2.getYear());
+
+            DateLiteral literal3 = new DateLiteral("0097-10-07", Type.DATE);
+            Assert.assertEquals(97, literal3.getYear());
+
+            DateLiteral literal4 = new DateLiteral("99-10-07", Type.DATE);
+            Assert.assertEquals(1999, literal4.getYear());
+
+            DateLiteral literal5 = new DateLiteral("70-10-07", Type.DATE);
+            Assert.assertEquals(1970, literal5.getYear());
+
+            DateLiteral literal6 = new DateLiteral("69-10-07", Type.DATE);
+            Assert.assertEquals(2069, literal6.getYear());
+
+            DateLiteral literal7 = new DateLiteral("00-10-07", Type.DATE);
+            Assert.assertEquals(2000, literal7.getYear());
+
+        } catch (AnalysisException e) {
+            e.printStackTrace();
+            hasException = true;
+        }
+        Assert.assertFalse(hasException);
+    }
+}