ASTERIXDB-1528: fix 101 query 6 and 7.

Change-Id: I35bbf838b152bdfd56efd523961ec1dc0ca8322d
Reviewed-on: https://asterix-gerrit.ics.uci.edu/1063
Sonar-Qube: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Integration-Tests: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Till Westmann <tillw@apache.org>
diff --git a/asterixdb/asterix-doc/src/site/markdown/aql/primer-sql-like.md b/asterixdb/asterix-doc/src/site/markdown/aql/primer-sql-like.md
index 397140f..9f15bb6 100644
--- a/asterixdb/asterix-doc/src/site/markdown/aql/primer-sql-like.md
+++ b/asterixdb/asterix-doc/src/site/markdown/aql/primer-sql-like.md
@@ -660,13 +660,13 @@
 The expressive power of AQL includes support for queries involving "some" (existentially quantified)
 and "all" (universally quantified) query semantics.
 As an example of an existential AQL query, here we show a query to list the Facebook users who are currently employed.
-Such employees will have an employment history containing a record with a null end-date value, which leads us to the
+Such employees will have an employment history containing a record with the end-date value missing, which leads us to the
 following AQL query:
 
         use dataverse TinySocial;
 
         from $fbu in dataset FacebookUsers
-        where (some $e in $fbu.employment satisfies is-null($e.end-date))
+        where (some $e in $fbu.employment satisfies is-missing($e.end-date))
         select $fbu;
 
 The expected result in this case is:
@@ -682,13 +682,13 @@
 
 ### Query 7 - Universal Quantification ###
 As an example of a universal AQL query, here we show a query to list the Facebook users who are currently unemployed.
-Such employees will have an employment history containing no records with null end-date values, leading us to the
+Such employees will have an employment history containing no records that miss end-date values, leading us to the
 following AQL query:
 
         use dataverse TinySocial;
 
         from $fbu in dataset FacebookUsers
-        where (every $e in $fbu.employment satisfies not(is-null($e.end-date)))
+        where (every $e in $fbu.employment satisfies not(is-missing($e.end-date)))
         select $fbu;
 
 Here is the expected result for our sample data:
diff --git a/asterixdb/asterix-doc/src/site/markdown/aql/primer.md b/asterixdb/asterix-doc/src/site/markdown/aql/primer.md
index f56eb93..35c870d 100644
--- a/asterixdb/asterix-doc/src/site/markdown/aql/primer.md
+++ b/asterixdb/asterix-doc/src/site/markdown/aql/primer.md
@@ -668,13 +668,13 @@
 The expressive power of AQL includes support for queries involving "some" (existentially quantified)
 and "all" (universally quantified) query semantics.
 As an example of an existential AQL query, here we show a query to list the Facebook users who are currently employed.
-Such employees will have an employment history containing a record with a null end-date value, which leads us to the
+Such employees will have an employment history containing a record with the end-date value missing, which leads us to the
 following AQL query:
 
         use dataverse TinySocial;
 
         for $fbu in dataset FacebookUsers
-        where (some $e in $fbu.employment satisfies is-null($e.end-date))
+        where (some $e in $fbu.employment satisfies is-missing($e.end-date))
         return $fbu;
 
 The expected result in this case is:
@@ -690,13 +690,13 @@
 
 ### Query 7 - Universal Quantification ###
 As an example of a universal AQL query, here we show a query to list the Facebook users who are currently unemployed.
-Such employees will have an employment history containing no records with null end-date values, leading us to the
+Such employees will have an employment history containing no records that miss end-date values, leading us to the
 following AQL query:
 
         use dataverse TinySocial;
 
         for $fbu in dataset FacebookUsers
-        where (every $e in $fbu.employment satisfies not(is-null($e.end-date)))
+        where (every $e in $fbu.employment satisfies not(is-missing($e.end-date)))
         return $fbu;
 
 Here is the expected result for our sample data: