sql之join练习

SELECT *from t_distribution;
SELECT *from t_department;


SELECT t_distribution.ad_area_code,t_distribution.area_num,t_department.ad_area_name
FROM t_distribution
LEFT JOIN t_department
ON t_distribution.ad_area_code =t_department.ad_area_id;

SELECT  A.ad_area_code,A.area_num,A.flag,t_department.ad_area_name
FROM t_distribution as A
RIGHT JOIN t_department
ON A.ad_area_code =t_department.ad_area_id;

SELECT t_distribution.area_num,t_distribution.ad_area_code,t_department.ad_area_name
FROM t_distribution
INNER  JOIN t_department
ON t_distribution.ad_area_code =t_department.ad_area_id

结果1：

结果2：

结果3：

结果4：

结果5：