What do the ALL and ANY operators do when used in a subquery?

QUESTION: What do the ALL and ANY operators do when used in a subquery?   [signinlocker] SOLUTION   ALL specifies that a condition is true for all values in a set of values. ANY specifies that the condition is true for at least one value in a set of values. [/signinlocker]

Which comparison operators can be used when searching for null values? Which comparison operators cannot be used when searching for null values?

QUESTION: Which comparison operators can be used when searching for null values? Which comparison operators cannot be used when searching for null values? What is the result when these unacceptable comparison operators are used when searching for null values?   [signinlocker] SOLUTION   None of the comparison operators except for IS NULL or IS NOT…