Sep 17, 2019 5:46:27 PM 共346人围观 0人评论

修改多表案例：

Sep 17, 2019 5:22:59 PM 共362人围观 0人评论

# 插入语句INSERT INTO jobname,jobVALUES '王五','市长';# 插入子查询INSERT INTO jobname,jobSELECT name,job FROM job WHERE name='张三';VALUSE和SET区别：insert into table field1,fiel......

Sep 17, 2019 4:53:40 PM 共370人围观 0人评论

案例：person表person_copy1表select * from person union all select * from person_copy1union all 不去重union 去重执行结果：去重SELECT id,cname FROM t_ca WHERE csex='男'UNION SE......

Sep 17, 2019 1:49:27 PM 共380人围观 0人评论

# WHERE后加子查询SELECT e.salary FROM employees e WHERE e.salarySELECT e.salary FROM employees e WHERE last_name='Abel';SELECT e.last_name,e.first_name,e.job_id,e.sa......

Sep 16, 2019 8:25:47 PM 共428人围观 0人评论

SELECT MAXemployees.salary,employees.job_id FROM employees GROUP BY employees.job_id;SELECT COUNT*,departments.location_id FROM departments GROUP BY location_id......