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 statement and no intermediate temp table.<\/p>\n
Note that you must write a single update statement, DO NOT write any select statement for this problem.<\/p>\n
Example:<\/p>\n
| id | name | sex | salary |
\n|—-|——|—–|——–|
\n| 1 | A | m | 2500 |
\n| 2 | B | f | 1500 |
\n| 3 | C | m | 5500 |
\n| 4 | D | f | 500 |
\nAfter running your update statement, the above salary table should have the following rows:
\n| id | name | sex | salary |
\n|—-|——|—–|——–|
\n| 1 | A | f | 2500 |
\n| 2 | B | m | 1500 |
\n| 3 | C | f | 5500 |
\n| 4 | D | m | 500 |<\/p>\n
Solution:<\/p>\n
\r\n\r\nUPDATE `salary` SET `sex` = CASE\r\n WHEN sex = 'm' THEN 'f'\r\n WHEN sex = 'f' THEN 'm'\r\n END\r\n\r\n<\/pre>\nThis may open up a possibility to optimize a massive amount of updates.<\/p>\n","protected":false},"excerpt":{"rendered":"