[SQL] [LeetCode] Challenge log 627

627. Swap Salary

Sql if and case statement:

update [table] set [column] = if ([condition], [v1], [v2] )

(see case example at the end)


Given a table

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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:

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| 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:

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

Soulution:
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UPDATE salary SET sex = IF(sex = 'm', 'f', 'm')
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-- alter
UPDATE salary
SET
sex = CASE sex
WHEN 'm' THEN 'f'
ELSE 'm'
END;

SQL case when
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SELECT player_name,
weight,
CASE WHEN weight > 250 THEN 'over 250'
WHEN weight > 200 THEN '201-250'
WHEN weight > 175 THEN '176-200'
ELSE '175 or under' END AS weight_group
FROM benn.college_football_players
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