MAX and MIN operator in SQL
(SELECT MAX (Mark) FROM EXAM_MARK WHERE StudentId = 'S1')
(SELECT MIN (Mark) FROM EXAM_MARK WHERE StudentId = 'S1')
Example needs no further explanation. SQL also has AVG for averages. Its counterparts aggregate AND and OR are spelled, respectively, EVERY and either SOME or ANY, but all of these must be used with care because of the consequences of the aforementioned general rule concerning the treatment of NULL. For example, if the condition c evaluates to UNKNOWN for every row of table t, or t is empty, then (SELECT EVERY(c) FROM t) evaluates to UNKNOWN, whereas when t is empty it really ought to evaluate to TRUE.