1 files changed, 11 insertions, 0 deletions
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/nullExpressions.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/nullExpressions.scala
index e22026d584..6a45249943 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/nullExpressions.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/nullExpressions.scala
@@ -34,6 +34,9 @@ import org.apache.spark.sql.types._
  *   coalesce(null, null, null) => null
  * }}}
  */
+@ExpressionDescription(
+  usage = "_FUNC_(a1, a2, ...) - Returns the first non-null argument if exists. Otherwise, NULL.",
+  extended = "> SELECT _FUNC_(NULL, 1, NULL);\n 1")
 case class Coalesce(children: Seq[Expression]) extends Expression {
 
   /** Coalesce is nullable if all of its children are nullable, or if it has no children. */
@@ -89,6 +92,8 @@ case class Coalesce(children: Seq[Expression]) extends Expression {
 /**
  * Evaluates to `true` iff it's NaN.
  */
+@ExpressionDescription(
+  usage = "_FUNC_(a) - Returns true if a is NaN and false otherwise.")
 case class IsNaN(child: Expression) extends UnaryExpression
   with Predicate with ImplicitCastInputTypes {
 
@@ -126,6 +131,8 @@ case class IsNaN(child: Expression) extends UnaryExpression
  * An Expression evaluates to `left` iff it's not NaN, or evaluates to `right` otherwise.
  * This Expression is useful for mapping NaN values to null.
  */
+@ExpressionDescription(
+  usage = "_FUNC_(a,b) - Returns a iff it's not NaN, or b otherwise.")
 case class NaNvl(left: Expression, right: Expression)
     extends BinaryExpression with ImplicitCastInputTypes {
 
@@ -180,6 +187,8 @@ case class NaNvl(left: Expression, right: Expression)
 /**
  * An expression that is evaluated to true if the input is null.
  */
+@ExpressionDescription(
+  usage = "_FUNC_(a) - Returns true if a is NULL and false otherwise.")
 case class IsNull(child: Expression) extends UnaryExpression with Predicate {
   override def nullable: Boolean = false
 
@@ -201,6 +210,8 @@ case class IsNull(child: Expression) extends UnaryExpression with Predicate {
 /**
  * An expression that is evaluated to true if the input is not null.
  */
+@ExpressionDescription(
+  usage = "_FUNC_(a) - Returns true if a is not NULL and false otherwise.")
 case class IsNotNull(child: Expression) extends UnaryExpression with Predicate {
   override def nullable: Boolean = false