SQL 语法学习

2017/2/13
查询：
SELECT * FROM c2_company;

唯一值：
SELECT DISTINCT company_type FROM c2_company;

更精确的查找：
SELECT * FROM c2_company c WHERE c.`COMPANY_NAME`='刘欢的de';

AND:
SELECT * FROM c2_company c WHERE c.`COMPANY_NAME`='刘欢的de' AND c.`COMPANY_TYPE`='T';

OR:
SELECT * FROM c2_company c WHERE c.`COMPANY_NAME`='刘欢的de' OR C.`COMPANY_TYPE`='R';

ORDER BY 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 ='欢欢波波' WHERE company_name ='刘欢的de';

DELETE 删除：
DELETE FROM c2_company WHERE company_name='bobo';

INSERT INTO 插入：
INSERT INTO c2_company(id,company_name) VALUES (6,huanhuan);

LIKE 模糊查询：
SELECT * FROM c2_company WHERE company_name LIKE '欢%';
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中语法 LIMIT ：
SELECT * FROM c2_company LIMIT 5;

ORACLE中语法 ：
SELECT * FROM c2_company WHERE rownum <='6';

IN 在where子句子中规定多个值：
SELECT * FROM c2_company WHERE company_type IN ('T','R');

BETWEEN ^ AND ^  选取这个范围内的值：
SELECT * FROM c2_company WHERE id BETWEEN 2 AND 40;

AS
alias 别名：列
SELECT id AS '排序',company_name AS'公司名称' FROM c2_company;

JOIN 通过两个或多个表相同的部分，把表结合起来：
通过两个表相同的部分进行结合：
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 表中至少有一个匹配：
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 从左表有符合条件的行，即使右表没有符合条件的行。
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  从右表有符合条件的行，即使左表没有符合条件的行。
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  只要某个表存在匹配
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 合并两个或多个 SELECT 语句的结果集
UNION 合并不重复：
SELECT E_Name FROM Employees_China
UNION
SELECT E_Name FROM Employees_USA;

UNION ALL 合并所有，会重复：
SELECT E_Name FROM Employees_China
UNION ALL
SELECT E_Name FROM Employees_USA;