SELECT shohin_bunrui,SUM(hanbai_tanka),SUM(shiire_tanka)FROM Shohin
GROUP BY shohin_bunrui;

CREATE VIEW 视图名称(<视图列名1>,<视图列名2>,...)
AS
<SELECT语句>

CREATE VIEW ShohinSum ( shohin_bunrui, cnt_shohin)
AS
SELECT shohin_bunrui,COUNT(*)FROM ShohinGROUP BY shohin_bunrui;

SELECT shohin_bunrui,cnt_shohinFROM ShohinSum;

CREATE VIEW ShohinSumJim (shohin_bunrui,cnt_shohin)
AS
SELECT shohin_bunrui,cnt_shohinFROM ShohinSumWHERE shohin_bunrui='办公用品';--确认是否创建出了视图
SEELCT shohin_bunrui,cnt_shohinFROM ShohinSumnJim;

CREATE VIEW ShohinJim (shohin_id,shohin_mei,shohin_bunrui,hanbai_tanka,shiire_tanka,torokubi)
AS
SELECT *FROM ShohinWHERE shohin_bunrui = '办公用品';

INSERT INTO ShohinJim VALUES ('0009','印章',‘办公用品’,95,10,'2009-11-30');

--PostgreSQLCREATE OR REPLACE RULE insert_rule
AS ON INSERT
TO ShohinJim DO INSTEAD
INSERT INTO Shohin VALUES(new.shohin_id,new.shohin_mei,new.shohin_bunrui,new.hanbai_tanka,new.shiire_tanka,new.torokubi);

--确认数据是否已经添加到视图中了
SELECT*FROM ShohinJim;

--确认数据是否已经添加到原表中了
SELECT*FROM Shohin;

DROP VIEW (<视图列名1>,<视图列名2>,......)

DROP VIEW ShohinSum;

DROP VIEW ShohinSum CASCADE;

--根据商品种类统计商品数量的视图
CREATE VIEW ShohinSum (shohin_bunrui,cnt_shohin)
AS
SELECT shohin_bunrui,COUNT(*)FROM ShohinGROUP BY Shohin_bunrui;--确认视图是否已经创建成功
SELECT shohin_bunrui,cnt_shohinFROM ShohinSum;

--SQL Server、DB2、PostgreSQL、MySQL
--直接在FROM子句中使用定义视图的SELECT语句SELECT shohin_bunrui,cnt_shohinFROM (SELECT shohin_bunrui,COUNT(*) AS cnt_shohinFROM ShohinGROUP BY shohin_bunrui) AS ShohinSum;

--SQL Server、DB2、PostgreSQL、MySQLSELECT shohin_bunrui,cnt_shohinFROM (SELECT * FROM ( SELECT  shohin_bunrui,COUNT(*) AS cnt_shohinFROM ShohinGROUP BY shohin_bunrui) AS ShohinSumWHERE cnt_shohin = 4 ) AS ShohinSum2;

SELECT AVG(hanbai_tanka)FROM Shohin;

SELECT shohin_id,shohin_mei,hanbai_tankaFROM ShohinWHERE hanbai_tanka > (SELECT AVG(hanbai_tanka)FROM Shohin);

SELECT   shohin_id,shohin_mei,hanbai_tanka,(SELECT AVG(hanbai_tanka)FROM Shohin) AS avg_tankaFROM Shohin;

SELECT shohin_bunrui,AVG(hanbai_tanka)FROM Shohin
GROUP BY shohin_bunrui
HAVING AVG(hanbai_tanka) > (SELECT AVG(hanbai_tanka)FROM Shohin);

--SQL、DB2、PostgreSQL，MySQL
SELECT shohin_id,shohin_mei,hanbai_tankaFROM Shohin AS S1WHERE hanbai_tanka > (SELECT AVG(hanbai_tanka)FROM Shohin AS S2WHERE S1.shohin_bunrui = S2.shohin_bunruiGROUP BY shohin_bunrui);