创建测试表
mysql> CREATE TABLE `product` (
-> `proID` int() NOT NULL AUTO_INCREMENT COMMENT '商品表主键',
-> `price` decimal(,) NOT NULL COMMENT '商品价格',
-> `type` int() NOT NULL COMMENT '商品类别(0生鲜,1食品,2生活)',
-> `dtime` datetime NOT NULL COMMENT '创建时间',
-> PRIMARY KEY (`proID`)
-> ) ENGINE=InnoDB AUTO_INCREMENT= DEFAULT CHARSET=utf8 COMMENT='商品表';
Query OK, rows affected (0.11 sec) mysql> CREATE TABLE `producttype` (
-> `ID` int() NOT NULL COMMENT '商品类别(0生鲜,1食品,2生活)',
-> `amount` int() COMMENT '每种类别商品总金额',
-> UNIQUE KEY (`ID`)
-> ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='商品类别资金汇总表'
-> ;
Query OK, rows affected (0.12 sec)
mysql> INSERT INTO product(price,type,dtime) VALUES(10.00,0,now()),(10.00,1,now()),(10.00,1,now()),(20.00,2,now()),(30.00,3,now());
Query OK, 5 rows affected (0.06 sec)
Records: 5 Duplicates: 0 Warnings: 0
mysql> INSERT INTO producttype(ID) VALUES(1),(2),(3);
Query OK, 3 rows affected (0.04 sec)
Records: 3 Duplicates: 0 Warnings: 0
mysql> select * from product;
+-------+-------+------+---------------------+
| proID | price | type | dtime |
+-------+-------+------+---------------------+
| | 10.00 | | -- :: |
| | 10.00 | | -- :: |
| | 10.00 | | -- :: |
| | 20.00 | | -- :: |
| | 30.00 | | -- :: |
+-------+-------+------+---------------------+
rows in set (0.00 sec) mysql> select * from producttype;
+----+--------+
| ID | amount |
+----+--------+
| | NULL |
| | NULL |
| | NULL |
+----+--------+
rows in set (0.00 sec)
1. 单表更新
UPDATE用法：update 表名 set 属性1=value1,属性2=value2 where 限定条件
示例：
mysql> UPDATE product
-> SET price='20.00',type=0
-> WHERE proID=2;
Query OK, 1 row affected (0.04 sec)
Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from product;
+-------+-------+------+---------------------+
| proID | price | type | dtime |
+-------+-------+------+---------------------+
| 1 | 10.00 | 0 | 2018-01-31 03:06:05 |
| 2 | 20.00 | 0 | 2018-01-31 03:06:05 |
| 3 | 10.00 | 1 | 2018-01-31 03:06:05 |
| 4 | 20.00 | 2 | 2018-01-31 03:06:05 |
| 5 | 30.00 | 3 | 2018-01-31 03:06:05 |
+-------+-------+------+---------------------+
5 rows in set (0.00 sec)
2. 关联更新
UPDATE用法：update 表名1,表名2 set 表1.属性=表2.属性值 where 限定条件
示例：
mysql> UPDATE producttype,product
-> SET producttype.amount=product.price
-> where product.TYPE = producttype.ID AND product.TYPE=1;
Query OK, 1 row affected (0.09 sec)
Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from producttype;
+----+--------+
| ID | amount |
+----+--------+
| 1 | 10 |
| 2 | NULL |
| 3 | NULL |
+----+--------+
3 rows in set (0.00 sec)
3. 限制更新
UPDATE用法：update 表名1,表名2 set 表1.属性=表2.属性值 where 限定条件 limit m
说明：只支持更新前多少行，而不支持非TOP的指定范围更新，也就是说，limit只接收一个参数。
意义：更新前m个符合where条件的记录。
mysql> UPDATE tb_name SET column_name='test' LIMIT ;
4. 排序更新
UPDATE用法：update 表名1,表名2 set 表1.属性=表2.属性值 where 限定条件 order by ... [limit m]
说明：同限制更新一样，首先判断出符合where条件的记录，然后对符合条件的记录进行排序，最后对排序后的前m条记录做更新
mysql> UPDATE tb_name SET column_name='test' ORDER BY id ASC LIMIT ;
5. 联合更新
UPDATE用法：update 表A set A.属性=表B.属性值 FROM a as A [inner join | right join | left join] b as B on [连接条件] where 限定条件
mysql> UPDATE Table_A
-> SET Table_A.col1 = Table_B.col1,
-> Table_A.col2 = Table_B.col2
-> FROM Some_Table AS Table_A
-> INNER JOIN Other_Table AS Table_B ON Table_A.id = Table_B.id
-> WHERE Table_A.col3 = 'cool';
mysql> update a join b on a.id=b.id set a.name=b.name where a.year=;