关于DB2内连接查询方式与from跟多表查询方式哪个效率高？

Question

select * from t_kjxm_resource,t_kjxm_qqpg,projectinfo where type=3 and t_kjxm_resource.KJXM_ID=t_kjxm_qqpg.ID and t_kjxm_resource.PROJECTINFO_ID=projectinfo.id;

select * from t_kjxm_resource join t_kjxm_qqpg on t_kjxm_resource.KJXM_ID=t_kjxm_qqpg.ID join projectinfo on  t_kjxm_resource.PROJECTINFO_ID=projectinfo.id where type=3;

Answer 1

尽是表连接的两种写法，where 表连接出现在较早的规范中，join出现在最新的规范中，性能没有差别

Answer 2

写在where里面和用join其实一样，只是不同的写法而已。不过因为写在where里面不不容易表现关联关系，现在推荐join写法