给出一个员工工资表,列 EmployeeID, Salary, 和 DepartmentID,写一个更新声明,增加销售部门的所有员工的工资7%.
The UPDATE statement to increase the salary of all employees in the Sales department by 7% would be:

```
UPDATE employee_salaries
SET Salary = Salary * 1.07
WHERE DepartmentID = 'Sales';
```

This statement will multiply the current salary of all employees in the Sales department by 1.07 (which is equivalent to a 7% increase), and update the Salary column with the new, increased salary value for those employees. The WHERE clause limits the update to only those employees who belong to the Sales department (based on their DepartmentID value).