Q627 added.

SQL/Q627.sql

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+--Table: Salary
+
+--+-------------+----------+
+--| Column Name | Type     |
+--+-------------+----------+
+--| id          | int      |
+--| name        | varchar  |
+--| sex         | ENUM     |
+--| salary      | int      |
+--+-------------+----------+
+--id is the primary key for this table.
+--The sex column is ENUM value of type ('m', 'f').
+--The table contains information about an employee.
+
+
+--Write an SQL query to 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 temporary tables.
+
+--Note that you must write a single update statement, do not write any select statement for this problem.
+
+UPDATE salary
+SET sex = CASE sex
+        WHEN 'm' THEN 'f'
+        ELSE 'm'
+    END;