2017/2/13
查詢：select * from c2_company;
唯一值：
select distinct company_type from c2_company;
更精確的查詢：
select * from c2_company c where c.`company_name`='劉歡的de';
and:
select * from c2_company c where c.`company_name`='劉歡的de' and c.`company_type`='t';
or:select * from c2_company c where c.`company_name`='劉歡的de' or c.`company_type`='r';
order by 公升序：
select * from c2_company order by parent_id;
desc 降序：
select * from c2_company order by parent_id desc;
update 修改：
update c2_company set company_name ='歡歡波波' where company_name ='劉歡的de';
delete 刪除：
delete from c2_company where company_name='bobo';
insert into 插入：
insert into c2_company(id,company_name) values (6,huanhuan);
like 模糊查詢：
select * from c2_company where company_name like '歡%';
select * from c2_company where company_name like '%商';
select * from c2_company where company_name like '%小玩意%';
select * from c2_company where company_name not like '%小玩意%';
top 摘取：
select top 5 * from c2_company;
select top 50 percent * from c2_comapny;
mysql中語法 limit ：
select * from c2_company limit 5;
oracle中語法 ：
select * from c2_company where rownum <='6';
in 在where子句子中規定多個值：
select * from c2_company where company_type in ('t','r');
between ^ and ^ 選取這個範圍內的值：
select * from c2_company where id between 2 and 40;
asalias 別名：列
select id as '排序',company_name as'公司名稱' from c2_company;
join 通過兩個或多個表相同的部分，把錶結合起來：
通過兩個表相同的部分進行結合：
select c2_company.`company_code`,c2_store.`back_number`from c2_company,c2_store
where c2_company.`area_id_fk`=c2_store.`area_id_fk`;
inner join ^ on 表中至少有乙個匹配：
select c2_company.`company_code`,c2_store.`counter_number` from c2_company inner join c2_store on c2_company.`area_id_fk`=c2_store.`area_id_fk`;
left join ^ on 從左表有符合條件的行，即使右表沒有符合條件的行。
select c2_company.`company_code`,c2_store.`counter_number` from c2_company left join c2_store on c2_company.`area_id_fk`=c2_store.`area_id_fk`;
right join ^ on 從右表有符合條件的行，即使左表沒有符合條件的行。
select c2_company.`company_code`,c2_store.`counter_number` from c2_company right join c2_store on c2_company.`area_id_fk`=c2_store.`area_id_fk`;
full join ^on 只要某個表存在匹配
select c2_company.`company_code`,c2_store.`counter_number` from c2_company full join c2_store on c2_company.`area_id_fk`=c2_store.`area_id_fk`;
union 合併兩個或多個 select 語句的結果集
union 合併不重複：
select e_name from employees_china
union
select e_name from employees_usa;
union all 合併所有，會重複：
select e_name from employees_china
union all
select e_name from employees_usa;
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