COALESCE(x, y, z, ...) Returns the first parameter that is not NULL.
GREATEST(x, y, z, ...) Returns the greatest value or greatest character string.
IF(expr, val1, val2) Returns val1 if expr is true; otherwise, val2.
IFNULL(expr1, expr2) Returns expr2 if expr1 is NULL; otherwise, expr1.
INTERVAL(x, n1, n2, ...) Returns 0 if xISNULL(x) Returns 1 or 0, according to whether x IS NULL holds.
LEAST(x, y, z, ...) Returns the smallest value or smallest character string.
STRCMP(s1, s2) Returns 0 if s1=s2 in sort order, -1 if s1s2.