| Just wanted to mention that there is an operator called IS DISTINCT FROM in SQL99 for that and add some links because I researched this topic a bit for
 HHH-10928 Closed http://stackoverflow.com/questions/10416789/how-to-rewrite-is-distinct-from-and-is-not-distinct-from
https://blog.jooq.org/2012/09/21/the-is-distinct-from-predicate/
https://www.ibm.com/support/knowledgecenter/SSEPEK_10.0.0/com.ibm.db2z10.doc.sqlref/src/tpc/db2z_distinctpredicate.html
https://wiki.postgresql.org/wiki/Is_distinct_from
http://www.firebirdsql.org/refdocs/langrefupd20-distinct.html
http://www.h2database.com/html/grammar.html#condition_right_hand_side
http://hsqldb.org/doc/guide/dataaccess-chapt.html#dac_sql_predicates |