关联子查询如果可能把它改成普通子查询：

botang

1. SELECT employee_id,salary,last_name FROM employees M
   
2. WHERE EXISTS
   
3. (SELECT 'X'  FROM employees W
   
4. WHERE (W.manager_id=M.employee_id) AND W.salary > 10000);
   
5. 
   
6. SELECT employee_id,salary,last_name FROM employees M
   
7. WHERE  employee_id in
   
8. (SELECT W.manager_id  FROM employees W
   
9. WHERE (W.manager_id=M.employee_id) AND W.salary > 10000);
   
10. 
    
11. SELECT employee_id,salary,last_name FROM employees M
    
12. WHERE   employee_id  in
    
13. (SELECT manager_id   FROM employees
    
14. WHERE  salary > 10000);
    
15. 
    
16. 
    
17. 
    
18. 
    
19. SELECT * FROM departments
    
20. WHERE NOT EXISTS
    
21. (SELECT * FROM employees
    
22. WHERE employees.department_id=departments.department_id);
    
23. 
    
24. 
    
25. SELECT * FROM departments
    
26. WHERE not exists
    
27. (SELECT 'X'   FROM employees
    
28. WHERE employees.department_id=departments.department_id);
    
29. 
    
30. SELECT * FROM departments
    
31. where department_id not in
    
32. (select  department_id  from employees  where department_id is not null  );
    
33. 
    
34. 
    

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