时间:2021-07-01 10:21:17 帮助过:16人阅读
- <code>SELECT
- last_name,job_id,e.department_id,department_name
- FROM
- employees AS e,departments AS d,locations AS l
- WHERE
- e.`department_id`=d.`department_id`
- AND
- d.`location_id`=l.`location_id`
- AND
- l.city=‘Toronto‘</code>
#案例;查询每个国家下的部门个数大于2的国家编号
- <code>SELECT
- country_id ,COUNT(*)
- FROM
- locations AS l,departments AS d
- WHERE
- l.`location_id`=d.`location_id`
- GROUP BY
- country_id
- HAVING
- COUNT(*) >2;</code>
mysql 多表查询案例
标签:location code from pre 员工 国家 try mysql 选中