8.leetCode627: Swap Salary

题目：Given a table salary, such as the one below, that has m=male and f=female values. Swap all f and m values (i.e., change all f values to m and vice versa) with a single update query and no intermediate temp table.

For example:

id name sex salary 1 A m 2500 2 B f 1500 3 C m 5500 4 D f 500

After running your query, the above salary table should have the following rows:

id name sex salary 1 A f 2500 2 B m 1500 3 C f 5500 4 D m 500

MySQL代码：

update salaryset   sex = case sex       when 'm' then 'f'       else 'm'   end