add round functions in o.a.s.sql.functions

Author: yjshen

sql/core/src/main/scala/org/apache/spark/sql/functions.scala

@@ -1385,6 +1385,30 @@ object functions {
    */
   def rint(columnName: String): Column = rint(Column(columnName))
 
+  /**
+   * Returns the value of the `e` rounded to 0 decimal places.
+   *
+   * @group math_funcs
+   * @since 1.5.0
+   */
+  def round(e: Column): Column = Round(Seq(e.expr))
+
+  /**
+   * Returns the value of `e` rounded to the value of `scale` decimal places.
+   *
+   * @group math_funcs
+   * @since 1.5.0
+   */
+  def round(e: Column, scale: Column): Column = Round(Seq(e.expr, scale.expr))
+
+  /**
+   * Returns the value of `e` rounded to `scale` decimal places.
+   *
+   * @group math_funcs
+   * @since 1.5.0
+   */
+  def round(e: Column, scale: Int): Column = round(e, lit(scale))
+
   /**
    * Shift the the given value numBits left. If the given value is a long value, this function
    * will return a long value else it will return an integer value.

sql/core/src/test/scala/org/apache/spark/sql/MathExpressionsSuite.scala

@@ -198,6 +198,16 @@ class MathExpressionsSuite extends QueryTest {
     testOneToOneMathFunction(rint, math.rint)
   }
 
+  test("round") {
+    checkAnswer(
+      ctx.sql("SELECT round(-32768), round(1809242.3151111344, 9), round(1809242.3151111344, 9)"),
+      Seq((1, 2)).toDF().select(
+        round(lit(-32768)),
+        round(lit(1809242.3151111344), lit(9)),
+        round(lit(1809242.3151111344), 9))
+    )
+  }
+
   test("exp") {
     testOneToOneMathFunction(exp, math.exp)
   }