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最新推荐文章于 2023-05-22 16:12:33 发布

原创最新推荐文章于 2023-05-22 16:12:33 发布 · 453 阅读

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本文提供了多个SQL查询示例，包括创建公共同义词、使用条件筛选员工记录、进行字符串操作以及联合查询等，适合数据库管理和开发人员学习与参考。

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create public synonym customers for hr.customers;

SELECT &1, "&2" FROM &3 WHERE last_name = '&4';

select * from hr.employees t where t.last_name='';
SELECT last_name, salary , hire_date FROM EMPLOYEES ORDER BY salary DESC;
SELECT last_name, salary , hire_date FROM EMPLOYEES ORDER BY 2 DESC;
select substr('1234567',0,3) from dual;

SELECT e.last_name, d.department_id, d.department_name, l.city
   FROM departments d
   LEFT OUTER JOIN employees e ON d.department_id = e.department_id
   left JOIN locations l ON d.location_id = l.location_id;
SELECT last_name, department_id, department_name, city
FROM departments d
JOIN employees e using(department_id) NATURAL JOIN locations l ;
SELECT 'Dear Customer ' || last_name || ',' as "dd" FROM employees;

select to_date('January 10 1999','mm dd yyyy') from dual;
SELECT LOWER(TRIM ('H' FROM 'HelloWorld')) FROM dual;