SQL学习基础
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创建表
CREATE TABLE Shohin
(
shohin_id CHAR(4) NOT NULL,
shohin_mei VARCHAR(100) NOT NULL,
shohin_bunrui VARCHAR(32) NOT NULL,
hanbai_tanka INTEGER,
shiire_tanka INTEGER,
torokubi DATE,
PRIMARY KEY (shohin_id)
);
更改表的名字:
RENAME TABLE Shohin TO Shohin1;由shohin改为shohin1;
或ALTER TABLE Shohin1 RENAME TO SHohin;由shohin改为shohin
更改列的数据类型
ALTER TABLE Shohin MODIFY Shohin_id CHAR(5);
同时更改列的名称和数据类型
ALTER TABLE Shohin CHANGE Shohin_id Shohin_id1 CHAR(4);
插入数据
START TRANSACTION;
INSERT INTO Shohin VALUES('0001','T恤衫','衣服',1000,500,'2009-09-20');
INSERT INTO Shohin VALUES('0002','打孔机','办公用品',500,320,'2009-09-11');
INSERT INTO Shohin VALUES('0003','运动T恤','衣服',4000,2800,NULL);
INSERT INTO Shohin VALUES('0004','菜刀','厨房用具',3000,2800,'2009-09-20');
INSERT INTO Shohin VALUES('0005','高压锅','厨房用具',6800,5000,'2009-01-15');
INSERT INTO Shohin VALUES('0006','叉子','厨房用具',500,NULL,'2009-09-20');
INSERT INTO Shohin VALUES('0007','擦菜板','厨房用具',880,790,'2008-04-28');
INSERT INTO Shohin VALUES('0008','圆珠笔','办公用品',100,NULL,'2009-09-11');
COMMIT;
常数的查询
SELECT '商品' AS Mojiretsu, 38 AS kazu,'2009-02-24' AS Hizuke,shohin_id,shohin_mei
FROM Shohin;
不重复查询
SELECT DISTINCT shohin_bunrui
FROM Shohin;--你好
SELECT DISTINCT shiire_tanka DISTINCT会把null项列出来
FROM Shohin;
使用SQL做四则运算
SELECT 1+2*3/2 AS "结果";
CREATE TABLE Shohin
(
shohin_id CHAR(4) NOT NULL,
shohin_mei VARCHAR(100) NOT NULL,
shohin_bunrui VARCHAR(32) NOT NULL,
hanbai_tanka INTEGER,
shiire_tanka INTEGER,
torokubi DATE,
PRIMARY KEY (shohin_id)
);
更改表的名字:
RENAME TABLE Shohin TO Shohin1;由shohin改为shohin1;
或ALTER TABLE Shohin1 RENAME TO SHohin;由shohin改为shohin
更改列的数据类型
ALTER TABLE Shohin MODIFY Shohin_id CHAR(5);
同时更改列的名称和数据类型
ALTER TABLE Shohin CHANGE Shohin_id Shohin_id1 CHAR(4);
插入数据
START TRANSACTION;
INSERT INTO Shohin VALUES('0001','T恤衫','衣服',1000,500,'2009-09-20');
INSERT INTO Shohin VALUES('0002','打孔机','办公用品',500,320,'2009-09-11');
INSERT INTO Shohin VALUES('0003','运动T恤','衣服',4000,2800,NULL);
INSERT INTO Shohin VALUES('0004','菜刀','厨房用具',3000,2800,'2009-09-20');
INSERT INTO Shohin VALUES('0005','高压锅','厨房用具',6800,5000,'2009-01-15');
INSERT INTO Shohin VALUES('0006','叉子','厨房用具',500,NULL,'2009-09-20');
INSERT INTO Shohin VALUES('0007','擦菜板','厨房用具',880,790,'2008-04-28');
INSERT INTO Shohin VALUES('0008','圆珠笔','办公用品',100,NULL,'2009-09-11');
COMMIT;
常数的查询
SELECT '商品' AS Mojiretsu, 38 AS kazu,'2009-02-24' AS Hizuke,shohin_id,shohin_mei
FROM Shohin;
不重复查询
SELECT DISTINCT shohin_bunrui
FROM Shohin;--你好
SELECT DISTINCT shiire_tanka DISTINCT会把null项列出来
FROM Shohin;
使用SQL做四则运算
SELECT 1+2*3/2 AS "结果";
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