Oracle筆記

查詢表結構:

select * from user_tab_columns where table_name = '大寫表名';

查看錶結構&字段註釋

select
	a.column_name,
	b.comments,
	a.DATA_TYPE || '(' || A .DATA_LENGTH || ')' 類型
from
	user_tab_columns a,
	user_col_comments b
where
	a.table_name = '大寫表名'
	and a.table_name = b.table_name
	and a.column_name = b.column_name

隨機查詢 N 條數據:

select * from (select * from [表名] order by sys_guid()) where rownum <= N;

遞歸查詢:

select * from [表名] start with [條件] connect by [子級字段] = prior [父級字段];

🌰【栗子】

-- 向下遞歸
select * from organization start with id = 10 connect by parent_id = prior id;
-- 向上遞歸
select * from organization start with id = 10 connect by id = prior parent_id;