NULL-values constraints NOT-NULL-constraint
range-locks isolation phantom-read transactions non-repeatable-reads
insignificant-whitespaces language-elements clauses statements predicates queries expressions
NULL-values General-Functions NULLIF
CASE-Function
operators logical-operators
sub-queries correlated-subquery synchronized-subquery
Oracle MySQL DB2 DROP-statement SQL-server DROP-INDEX MS-Access
collation binary-collation character-sets
join cross-join inner-join