SQL查询的时间和空间复杂性

Question

我们希望了解所有员工及其雇用日期，以便他们的雇佣日期大于雇佣人员的雇用日期＆＃39;戴维斯＆＃39;这两个问题在时间和空间复杂性方面如何相互比较？

SELECT e.last_name, e.hire_date 
FROM employees e 
JOIN employees davies ON (davies.last_name = 'Davies') 
WHERE davies.hire_date < e.hire_date; 

SELECT e.last_name, e.hire_date 
FROM employees e 
JOIN employees davies ON (davies.hire_date < e.hire_date) 
WHERE davies.last_name = 'Davies';

Answer 1

你可能正在寻找这个

SELECT e.last_name, e.hire_date 
FROM employees e 
WHERE e.hire_date > (SELECT TOP (1) hire_date FROM employees WHERE last_name = 'Davies')