diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/datetimeFunctions.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/datetimeFunctions.scala
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@@ -0,0 +1,191 @@
+/*
+ * 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.spark.sql.catalyst.expressions
+
+import java.util.{TimeZone, Calendar}
+
+import org.apache.spark.sql.catalyst.analysis.TypeCheckResult
+import org.apache.spark.sql.catalyst.util.DateTimeUtils
+import org.apache.spark.sql.types._
+import org.apache.spark.unsafe.types.UTF8String
+
+/**
+ * Returns the date that is num_months after start_date.
+ */
+case class AddMonths(startDate: Expression, months: Expression) extends Expression {
+  override def children: Seq[Expression] = startDate :: months :: Nil
+
+  override def foldable: Boolean = startDate.foldable && months.foldable
+  override def nullable: Boolean = startDate.nullable || months.nullable
+
+  override def checkInputDataTypes(): TypeCheckResult = {
+    val supportedLeftType = Seq(StringType, DateType, TimestampType, NullType)
+    if (!supportedLeftType.contains(startDate.dataType)) {
+      TypeCheckResult.TypeCheckFailure(
+        s"type of startdate expression in AddMonths should be string/timestamp/date," +
+          s" not ${startDate.dataType}")
+    } else if (months.dataType != IntegerType && months.dataType != NullType) {
+      TypeCheckResult.TypeCheckFailure(
+        s"type of months expression in AddMonths should be int, not ${months.dataType}.")
+    } else {
+      TypeCheckResult.TypeCheckSuccess
+    }
+  }
+
+  override def dataType: DataType = DateType
+
+  private val calendar = Calendar.getInstance()
+
+  override def eval(input: InternalRow): Any = {
+    val start = startDate.eval(input)
+    if (start == null) {
+      null
+    } else {
+      val m = months.eval(input)
+      if (m == null) {
+        null
+      } else {
+        val resultDayMillis = startDate.dataType match {
+          case StringType =>
+            DateTimeUtils.stringToTime(start.asInstanceOf[UTF8String].toString).getTime
+          case TimestampType =>
+            start.asInstanceOf[Long] * 100L
+          case DateType => DateTimeUtils.toMillisSinceEpoch(start.asInstanceOf[Int])
+        }
+        calendar.setTime(new java.util.Date(resultDayMillis))
+        calendar.add(Calendar.MONTH, m.asInstanceOf[Int])
+        DateTimeUtils.millisToDays(calendar.getTime.getTime)
+      }
+    }
+  }
+
+}
+
+/**
+ * Returns number of months between dates date1 and date2.
+ */
+case class MonthsBetween(date1: Expression, date2: Expression) extends Expression {
+  override def children: Seq[Expression] = date1 :: date2 :: Nil
+
+  override def foldable: Boolean = date1.foldable && date2.foldable
+  override def nullable: Boolean = date1.nullable || date2.nullable
+
+  override def checkInputDataTypes(): TypeCheckResult = {
+    val supportedType = Seq(StringType, DateType, TimestampType, NullType)
+    if (!supportedType.contains(date1.dataType)) {
+      TypeCheckResult.TypeCheckFailure(
+        s"type of date1 expression in MonthsBetween should be string/timestamp/date," +
+          s" not ${date1.dataType}")
+    } else if (!supportedType.contains(date2.dataType)) {
+      TypeCheckResult.TypeCheckFailure(
+        s"type of date2 expression in MonthsBetween should be string/timestamp/date," +
+          s" not ${date2.dataType}")
+    } else {
+      TypeCheckResult.TypeCheckSuccess
+    }
+  }
+
+  override def dataType: DataType = DoubleType
+  private val calendar = Calendar.getInstance()
+
+  override def eval(input: InternalRow): Any = {
+    val d1 = date1.eval(input)
+    val d2 = date2.eval(input)
+    if (d1 == null || d2 == null) {
+      null
+    } else {
+      def extractDays(raw: Any, dt: DataType): Long = dt match {
+        case StringType =>
+          DateTimeUtils.stringToTime(raw.asInstanceOf[UTF8String].toString).getTime
+        case TimestampType =>
+          raw.asInstanceOf[Long] * 100L
+        case DateType => DateTimeUtils.toMillisSinceEpoch(raw.asInstanceOf[Int])
+      }
+      calendar.setTime(new java.util.Date(extractDays(d1, date1.dataType)))
+      val dom1 = calendar.get(Calendar.DAY_OF_MONTH)
+      val y1 = calendar.get(Calendar.YEAR)
+      val m1 = calendar.get(Calendar.MONTH)
+      val daysInMonth1 = calendar.getMaximum(Calendar.DAY_OF_MONTH)
+      calendar.setTime(new java.util.Date(extractDays(d2, date2.dataType)))
+      val dom2 = calendar.get(Calendar.DAY_OF_MONTH)
+      val y2 = calendar.get(Calendar.YEAR)
+      val m2 = calendar.get(Calendar.MONTH)
+      val daysInMonth2 = calendar.getMaximum(Calendar.DAY_OF_MONTH)
+      if (dom1 == dom2 || (dom1 == daysInMonth1 && dom2 == daysInMonth2)) {
+        ((y1 - y2) * 12 + (m1 - m2)).toDouble
+      } else {
+        ((y1 - y2) * 12 + (m1 - m2)).toDouble + (dom1 - dom2).toDouble / 31.0
+      }
+    }
+  }
+}
+
+case class DateDiff(endDate: Expression, startDate: Expression) extends Expression {
+
+  override def children: Seq[Expression] = startDate :: endDate :: Nil
+
+  override def foldable: Boolean = startDate.foldable && endDate.foldable
+  override def nullable: Boolean = startDate.nullable || endDate.nullable
+
+  override def checkInputDataTypes(): TypeCheckResult = {
+    val supportedType = Seq(StringType, DateType, TimestampType, NullType)
+    if (!supportedType.contains(startDate.dataType)) {
+      TypeCheckResult.TypeCheckFailure(
+        s"type of startdate expression in DateDiff should be string/timestamp/date," +
+          s" not ${startDate.dataType}")
+    } else if (!supportedType.contains(endDate.dataType)) {
+      TypeCheckResult.TypeCheckFailure(
+        s"type of enddate expression in DateDiff should be string/timestamp/date," +
+          s" not ${endDate.dataType}")
+    } else {
+      TypeCheckResult.TypeCheckSuccess
+    }
+  }
+
+  override def dataType: DataType = IntegerType
+
+  override def toString: String = s"DateDiff($endDate, $startDate)"
+
+  private val MILLIS_PER_DAY = 86400000
+
+  @transient private val LOCAL_TIMEZONE = new ThreadLocal[TimeZone] {
+    override protected def initialValue: TimeZone = {
+      Calendar.getInstance.getTimeZone
+    }
+  }
+
+  override def eval(input: InternalRow): Any = {
+    val end = endDate.eval(input)
+    val start = startDate.eval(input)
+    if (start == null || end == null) {
+      null
+    } else {
+      def extractUTCDays(raw: Any, dt: DataType): Int = {
+        val localTime = dt match {
+          case StringType => DateTimeUtils.stringToTime(raw.asInstanceOf[UTF8String].toString).getTime
+          case TimestampType => DateTimeUtils.toJavaTimestamp(raw.asInstanceOf[Long]).getTime
+          case DateType => DateTimeUtils.toJavaDate(raw.asInstanceOf[Int]).getTime
+        }
+        val utcTime = localTime + LOCAL_TIMEZONE.get().getOffset(localTime)
+        (utcTime / MILLIS_PER_DAY).toInt
+      }
+      extractUTCDays(end, endDate.dataType) - extractUTCDays(start, startDate.dataType)
+      //extractDays(end, endDate.dataType) - extractDays(start, startDate.dataType)
+    }
+  }
+}