KwCheng's blog

1. in  , 

example : select * from monday where category in('3')

選出在monday這個資料表中category = 3 的資料.

2.cross join

example : select id_cid.cid , u_tto.tid from id_cid cross join u_tto where id_cid.id = u_tto.did limit 0,30

將兩個資料表進行cross join , 不過只會cross id相同的資料.

3. insert into

example : insert into id_cid (id , c_id) select id , category from monday

由monday這個資料表中選出id與category兩個column , 插入到id_cid這個資料表的欄位中.

4. select two items

example : SELECT cid_id_tid.cid, cid_id_tid.tid FROM cid_id_tid

5. add column

example : ALTER TABLE customers ADD Discount VARCHAR(10);

( VARCHAR : A string of variable length)

6.drop column

example : ALTER TABLE table_name DROP COLUMN column_name

7.中文的欄位 , 其屬性要設定為utf8 (unicode)