PostgreSQL数据库事务插入删除及更新操作示例

CREATE TABLE ProductIns
(product_id      CHAR(4)      NOT NULL,
 product_name    VARCHAR(100) NOT NULL,
 product_type    VARCHAR(32)  NOT NULL,
 sale_price      INTEGER      DEFAULT 0,
 purchase_price  INTEGER      ,
 regist_date     DATE         ,
 PRIMARY KEY (product_id));

INSERT INTO <表名> (列1,列2,...) VALUES (值1,值2,...);

INSERT INTO ProductIns (product_id, product_name, product_type, sale_price, purchase_price, regist_date) VALUES ('0001', 'T恤' ,'衣服', 1000, 500, '2222-09-20');

INSERT INTO ProductIns VALUES ('0005', '铁锅', '厨房用具', 6800, 5000, '2222-01-15');

INSERT INTO ProductIns VALUES ('0006', '勺子', '厨房用具', 500, NULL, '2222-09-20');

--显式方法设置默认值
INSERT INTO ProductIns VALUES ('0007', '筷子', '厨房用具', DEFAULT, 790, '2222-04-28');

--隐式方法设置默认值
INSERT INTO ProductIns (product_id, product_name, product_type, purchase_price, regist_date) VALUES ('0007', '筷子', '厨房用具', 790, '2222-04-28');

CREATE TABLE ProductCopy
(product_id      CHAR(4)      NOT NULL,
 product_name    VARCHAR(100) NOT NULL,
 product_type    VARCHAR(32)  NOT NULL,
 sale_price      INTEGER      ,
 purchase_price  INTEGER      ,
 regist_date     DATE         ,
 PRIMARY KEY (product_id));

INSERT INTO ProductCopy (product_id, product_name, product_type, sale_price, purchase_price, regist_date)
SELECT product_id, product_name, product_type, sale_price, purchase_price, regist_date
  FROM Product;

CREATE TABLE ProductType
(product_type        VARCHAR(32)  NOT NULL,
 sum_sale_price      INTEGER      ,
 sum_purchase_price  INTEGER      ,
 PRIMARY KEY (product_type));

INSERT INTO ProductType (product_type, sum_sale_price, sum_purchase_price)
SELECT product_type, SUM(sale_price), SUM(purchase_price)
  FROM Product
 GROUP BY product_type;

格式
DELETE FROM <表名>;
例子
DELETE FROM Product;

格式
DELETE FROM <表名>
WHERE <条件>;
例子
DELETE FROM Product
WHERE sale_price >= 2000;

UPDATE <表名>
SET <列名> = <表达式>;

UPDATE Product
   SET regist_date = '2222-02-02';

UPDATE <表名>
SET <列名> = <表达式>
WHERE <条件>;

UPDATE Product
   SET sale_price = sale_price * 10
 WHERE product_type = '厨房用具';

UPDATE Product
   SET regist_date = NULL
 WHERE product_id = '0008';

-- 使用逗号，所有DBMS中均可使用
UPDATE Product
   SET sale_price = sale_price * 10,
       purchase_price = purchase_price / 2
 WHERE product_type = '厨房用具';

-- 列表形式，在某些DBMS中无法使用
UPDATE Product
   SET (sale_price, purchase_price) = (sale_price * 10, purchase_price / 2)
 WHERE product_type = '厨房用具';

事务开始语句;
DML语句1;
DML语句2;
...
事务结束语句;

--PostgreSQL
BEGIN TRANSACTION;
    UPDATE Product
       SET sale_price = sale_price + 1000
     WHERE product_name = 'T恤';
    UPDATE Product
       SET sale_price = sale_price - 1000
     WHERE product_name = '裤子';
COMMIT;