目录
第3章 使用MySQL
入门命令
# 返回表的每一个字段
mysql> show columns from customers;
+--------------+-----------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+--------------+-----------+------+-----+---------+----------------+
| cust_id | int(11) | NO | PRI | NULL | auto_increment |
| cust_name | char(50) | NO | | NULL | |
| cust_address | char(50) | YES | | NULL | |
| cust_city | char(50) | YES | | NULL | |
| cust_state | char(5) | YES | | NULL | |
| cust_zip | char(10) | YES | | NULL | |
| cust_country | char(50) | YES | | NULL | |
| cust_contact | char(50) | YES | | NULL | |
| cust_email | char(255) | YES | | NULL | |
+--------------+-----------+------+-----+---------+----------------+
9 rows in set (0.00 sec)
# 还可以使用describe语句
mysql> describe customers;
+--------------+-----------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+--------------+-----------+------+-----+---------+----------------+
| cust_id | int(11) | NO | PRI | NULL | auto_increment |
| cust_name | char(50) | NO | | NULL | |
| cust_address | char(50) | YES | | NULL | |
| cust_city | char(50) | YES | | NULL | |
| cust_state | char(5) | YES | | NULL | |
| cust_zip | char(10) | YES | | NULL | |
| cust_country | char(50) | YES | | NULL | |
| cust_contact | char(50) | YES | | NULL | |
| cust_email | char(255) | YES | | NULL | |
+--------------+-----------+------+-----+---------+----------------+
9 rows in set (0.00 sec)
# 显示创建数据库的语句
mysql> show create database sys;
+----------+--------------------------------------------------------------+
| Database | Create Database |
+----------+--------------------------------------------------------------+
| sys | CREATE DATABASE `sys` /*!40100 DEFAULT CHARACTER SET utf8 */ |
+----------+--------------------------------------------------------------+
1 row in set (0.00 sec)
# 显示创建数据库表的语句
mysql> show create table customers;
+-----------+----+
| Table | Create Table
+-----------+----+
| customers | CREATE TABLE `customers` (
`cust_id` int(11) NOT NULL AUTO_INCREMENT,
`cust_name` char(50) NOT NULL,
`cust_address` char(50) DEFAULT NULL,
`cust_city` char(50) DEFAULT NULL,
`cust_state` char(5) DEFAULT NULL,
`cust_zip` char(10) DEFAULT NULL,
`cust_country` char(50) DEFAULT NULL,
`cust_contact` char(50) DEFAULT NULL,
`cust_email` char(255) DEFAULT NULL,
PRIMARY KEY (`cust_id`)
) ENGINE=InnoDB AUTO_INCREMENT=10006 DEFAULT CHARSET=utf8
+-----------+----+
1 row in set (0.00 sec)
第4章 检索数据
检索单列
mysql> select prod_name from products;
+----------------+
| prod_name |
+----------------+
| .5 ton anvil |
| 1 ton anvil |
| 2 ton anvil |
| Detonator |
| Bird seed |
| Carrots |
| Fuses |
| JetPack 1000 |
| JetPack 2000 |
| Oil can |
| Safe |
| Sling |
| TNT (1 stick) |
| TNT (5 sticks) |
+----------------+
14 rows in set (0.00 sec)
检索多列
mysql> select prod_id, prod_name, prod_price from products;
+---------+----------------+------------+
| prod_id | prod_name | prod_price |
+---------+----------------+------------+
| ANV01 | .5 ton anvil | 5.99 |
| ANV02 | 1 ton anvil | 9.99 |
| ANV03 | 2 ton anvil | 14.99 |
| DTNTR | Detonator | 13.00 |
| FB | Bird seed | 10.00 |
| FC | Carrots | 2.50 |
| FU1 | Fuses | 3.42 |
| JP1000 | JetPack 1000 | 35.00 |
| JP2000 | JetPack 2000 | 55.00 |
| OL1 | Oil can | 8.99 |
| SAFE | Safe | 50.00 |
| SLING | Sling | 4.49 |
| TNT1 | TNT (1 stick) | 2.50 |
| TNT2 | TNT (5 sticks) | 10.00 |
+---------+----------------+------------+
14 rows in set (0.00 sec)
检索所有列
mysql> select * from products;
+---------+---------+----------------+------------+----------------------------------------------------------------+
| prod_id | vend_id | prod_name | prod_price | prod_desc |
+---------+---------+----------------+------------+----------------------------------------------------------------+
| ANV01 | 1001 | .5 ton anvil | 5.99 | .5 ton anvil, black, complete with handy hook |
| ANV02 | 1001 | 1 ton anvil | 9.99 | 1 ton anvil, black, complete with handy hook and carrying case |
| ANV03 | 1001 | 2 ton anvil | 14.99 | 2 ton anvil, black, complete with handy hook and carrying case |
| DTNTR | 1003 | Detonator | 13.00 | Detonator (plunger powered), fuses not included |
| FB | 1003 | Bird seed | 10.00 | Large bag (suitable for road runners) |
| FC | 1003 | Carrots | 2.50 | Carrots (rabbit hunting season only) |
| FU1 | 1002 | Fuses | 3.42 | 1 dozen, extra long |
| JP1000 | 1005 | JetPack 1000 | 35.00 | JetPack 1000, intended for single use |
| JP2000 | 1005 | JetPack 2000 | 55.00 | JetPack 2000, multi-use |
| OL1 | 1002 | Oil can | 8.99 | Oil can, red |
| SAFE | 1003 | Safe | 50.00 | Safe with combination lock |
| SLING | 1003 | Sling | 4.49 | Sling, one size fits all |
| TNT1 | 1003 | TNT (1 stick) | 2.50 | TNT, red, single stick |
| TNT2 | 1003 | TNT (5 sticks) | 10.00 | TNT, red, pack of 10 sticks |
+---------+---------+----------------+------------+----------------------------------------------------------------+
14 rows in set (0.00 sec)
检索不同的行
mysql> select distinct vend_id from products;
+---------+
| vend_id |
+---------+
| 1001 |
| 1002 |
| 1003 |
| 1005 |
+---------+
4 rows in set (0.00 sec)
限制结果
# 从第0行开始，显示3行
mysql> select distinct vend_id from products limit 3;
# 或者 select distinct vend_id from products limit 0, 3;
# 或者 select distinct vend_id from products limit 3 offset 0;
+---------+
| vend_id |
+---------+
| 1001 |
| 1002 |
| 1003 |
+---------+
3 rows in set (0.00 sec)
第5章 排序检索
排序数据
mysql> select prod_name from products order by prod_name;
+----------------+
| prod_name |
+----------------+
| .5 ton anvil |
| 1 ton anvil |
| 2 ton anvil |
| Bird seed |
| Carrots |
| Detonator |
| Fuses |
| JetPack 1000 |
| JetPack 2000 |
| Oil can |
| Safe |
| Sling |
| TNT (1 stick) |
| TNT (5 sticks) |
+----------------+
按多个列排序
mysql> select prod_id, prod_price, prod_name from products order by prod_price, prod_name;
+---------+------------+----------------+
| prod_id | prod_price | prod_name |
+---------+------------+----------------+
| FC | 2.50 | Carrots |
| TNT1 | 2.50 | TNT (1 stick) |
| FU1 | 3.42 | Fuses |
| SLING | 4.49 | Sling |
| ANV01 | 5.99 | .5 ton anvil |
| OL1 | 8.99 | Oil can |
| ANV02 | 9.99 | 1 ton anvil |
| FB | 10.00 | Bird seed |
| TNT2 | 10.00 | TNT (5 sticks) |
| DTNTR | 13.00 | Detonator |
| ANV03 | 14.99 | 2 ton anvil |
| JP1000 | 35.00 | JetPack 1000 |
| SAFE | 50.00 | Safe |
| JP2000 | 55.00 | JetPack 2000 |
+---------+------------+----------------+
14 rows in set (0.00 sec)
指定排序方向
mysql> select prod_id, prod_price, prod_name from products order by prod_price desc;
+---------+------------+----------------+
| prod_id | prod_price | prod_name |
+---------+------------+----------------+
| JP2000 | 55.00 | JetPack 2000 |
| SAFE | 50.00 | Safe |
| JP1000 | 35.00 | JetPack 1000 |
| ANV03 | 14.99 | 2 ton anvil |
| DTNTR | 13.00 | Detonator |
| FB | 10.00 | Bird seed |
| TNT2 | 10.00 | TNT (5 sticks) |
| ANV02 | 9.99 | 1 ton anvil |
| OL1 | 8.99 | Oil can |
| ANV01 | 5.99 | .5 ton anvil |
| SLING | 4.49 | Sling |
| FU1 | 3.42 | Fuses |
| FC | 2.50 | Carrots |
| TNT1 | 2.50 | TNT (1 stick) |
+---------+------------+----------------+
14 rows in set (0.00 sec)
order by 和 limit 组合使用
mysql> select prod_id, prod_price, prod_name from products order by prod_price desc limit 3 offset 0;
+---------+------------+--------------+
| prod_id | prod_price | prod_name |
+---------+------------+--------------+
| JP2000 | 55.00 | JetPack 2000 |
| SAFE | 50.00 | Safe |
| JP1000 | 35.00 | JetPack 1000 |
+---------+------------+--------------+
3 rows in set (0.00 sec)
第6章 过滤数据
检查单个值
mysql> select prod_name, prod_price from products where prod_name='fuses';
+-----------+------------+
| prod_name | prod_price |
+-----------+------------+
| Fuses | 3.42 |
+-----------+------------+
1 row in set (0.00 sec)
不匹配检查
mysql> select vend_id, prod_name from products where vend_id <> 1003;
+---------+--------------+
| vend_id | prod_name |
+---------+--------------+
| 1001 | .5 ton anvil |
| 1001 | 1 ton anvil |
| 1001 | 2 ton anvil |
| 1002 | Fuses |
| 1005 | JetPack 1000 |
| 1005 | JetPack 2000 |
| 1002 | Oil can |
+---------+--------------+
7 rows in set (0.00 sec)
范围值检查
mysql> select prod_price, prod_name from products where prod_price between 5 and 10;
+------------+----------------+
| prod_price | prod_name |
+------------+----------------+
| 5.99 | .5 ton anvil |
| 9.99 | 1 ton anvil |
| 10.00 | Bird seed |
| 8.99 | Oil can |
| 10.00 | TNT (5 sticks) |
+------------+----------------+
5 rows in set (0.00 sec)
空值检查
mysql> select cust_name, cust_email from customers where cust_email is null;
+-------------+------------+
| cust_name | cust_email |
+-------------+------------+
| Mouse House | NULL |
| E Fudd | NULL |
+-------------+------------+
2 rows in set (0.00 sec)
第7章 数据过滤
组合where子句
and操作符
mysql> select prod_name, vend_id, prod_price from products where vend_id = 1003 and prod_price < 5;
+---------------+---------+------------+
| prod_name | vend_id | prod_price |
+---------------+---------+------------+
| Carrots | 1003 | 2.50 |
| Sling | 1003 | 4.49 |
| TNT (1 stick) | 1003 | 2.50 |
+---------------+---------+------------+
3 rows in set (0.01 sec)
or操作符
mysql> select prod_name, vend_id, prod_price from products where vend_id = 1003 or prod_price < 5;
+----------------+---------+------------+
| prod_name | vend_id | prod_price |
+----------------+---------+------------+
| Detonator | 1003 | 13.00 |
| Bird seed | 1003 | 10.00 |
| Carrots | 1003 | 2.50 |
| Fuses | 1002 | 3.42 |
| Safe | 1003 | 50.00 |
| Sling | 1003 | 4.49 |
| TNT (1 stick) | 1003 | 2.50 |
| TNT (5 sticks) | 1003 | 10.00 |
+----------------+---------+------------+
8 rows in set (0.00 sec)
计算次序
# and 优先级高于or
# 找出vend_id为1002或1003，并且prod_id大于等于10的产品
mysql> select prod_name, vend_id, prod_price from products where (vend_id = 1003 or vend_id = 1002) and prod_price >= 10;
+----------------+---------+------------+
| prod_name | vend_id | prod_price |
+----------------+---------+------------+
| Detonator | 1003 | 13.00 |
| Bird seed | 1003 | 10.00 |
| Safe | 1003 | 50.00 |
| TNT (5 sticks) | 1003 | 10.00 |
+----------------+---------+------------+
4 rows in set (0.00 sec)
in操作符
mysql> select prod_name, vend_id, prod_price from products where vend_id in (1002, 1003) order by prod_price desc;
+----------------+---------+------------+
| prod_name | vend_id | prod_price |
+----------------+---------+------------+
| Safe | 1003 | 50.00 |
| Detonator | 1003 | 13.00 |
| Bird seed | 1003 | 10.00 |
| TNT (5 sticks) | 1003 | 10.00 |
| Oil can | 1002 | 8.99 |
| Sling | 1003 | 4.49 |
| Fuses | 1002 | 3.42 |
| Carrots | 1003 | 2.50 |
| TNT (1 stick) | 1003 | 2.50 |
+----------------+---------+------------+
9 rows in set (0.00 sec)
not操作符
mysql> select prod_name, vend_id, prod_price from products where vend_id not in (1002, 1003) order by prod_price desc;
+--------------+---------+------------+
| prod_name | vend_id | prod_price |
+--------------+---------+------------+
| JetPack 2000 | 1005 | 55.00 |
| JetPack 1000 | 1005 | 35.00 |
| 2 ton anvil | 1001 | 14.99 |
| 1 ton anvil | 1001 | 9.99 |
| .5 ton anvil | 1001 | 5.99 |
+--------------+---------+------------+
5 rows in set (0.00 sec)
第8章 使用通配符进行过滤
%通配符
# %表示任何字符出现任意次数【0、1、多】次
mysql> select prod_name, prod_price from products where prod_name like 'jet%';
+--------------+------------+
| prod_name | prod_price |
+--------------+------------+
| JetPack 1000 | 35.00 |
| JetPack 2000 | 55.00 |
+--------------+------------+
2 rows in set (0.00 sec)
_通配符
# _通配符和%一样，只是_只匹配一个字符而不是多个字符
mysql> select prod_id, prod_name, prod_price from products where prod_name like '_ ton anvil';
+---------+-------------+------------+
| prod_id | prod_name | prod_price |
+---------+-------------+------------+
| ANV02 | 1 ton anvil | 9.99 |
| ANV03 | 2 ton anvil | 14.99 |
+---------+-------------+------------+
第9章 用正则表达式进行搜索
基本字符匹配
mysql> select prod_name, prod_price from products where prod_name regexp '1000';
+--------------+------------+
| prod_name | prod_price |
+--------------+------------+
| JetPack 1000 | 35.00 |
+--------------+------------+
1 row in set (0.00 sec)
mysql> select prod_name, prod_price from products where prod_name regexp '.000' order by prod_price desc;
+--------------+------------+
| prod_name | prod_price |
+--------------+------------+
| JetPack 2000 | 55.00 |
| JetPack 1000 | 35.00 |
+--------------+------------+
2 rows in set (0.00 sec)
进行OR匹配
mysql> select prod_name, prod_price from products where prod_name regexp '1000|2000' order by prod_price desc;
+--------------+------------+
| prod_name | prod_price |
+--------------+------------+
| JetPack 2000 | 55.00 |
| JetPack 1000 | 35.00 |
+--------------+------------+
2 rows in set (0.00 sec)
匹配几个字符之一
mysql> select prod_name, prod_price from products where prod_name regexp '[123] ton' order by prod_price desc;
+-------------+------------+
| prod_name | prod_price |
+-------------+------------+
| 2 ton anvil | 14.99 |
| 1 ton anvil | 9.99 |
+-------------+------------+
2 rows in set (0.00 sec)
匹配范围
mysql> select prod_name, prod_price from products where prod_name regexp '[1-5] ton' order by prod_price desc;
+--------------+------------+
| prod_name | prod_price |
+--------------+------------+
| 2 ton anvil | 14.99 |
| 1 ton anvil | 9.99 |
| .5 ton anvil | 5.99 |
+--------------+------------+
3 rows in set (0.00 sec)
匹配特殊字符
mysql> select prod_name, prod_price from products where prod_name regexp '\.';
+--------------+------------+
| prod_name | prod_price |
+--------------+------------+
| .5 ton anvil | 5.99 |
+--------------+------------+
1 row in set (0.00 sec)
匹配多个实例
mysql> select prod_name, prod_price from products where prod_name regexp '\([0-9] sticks?\)';
+----------------+------------+
| prod_name | prod_price |
+----------------+------------+
| TNT (1 stick) | 2.50 |
| TNT (5 sticks) | 10.00 |
+----------------+------------+
2 rows in set (0.00 sec)
定位符
mysql> select prod_name, prod_price from products where prod_name regexp '^[0-9\.]';
+--------------+------------+
| prod_name | prod_price |
+--------------+------------+
| .5 ton anvil | 5.99 |
| 1 ton anvil | 9.99 |
| 2 ton anvil | 14.99 |
+--------------+------------+
3 rows in set (0.00 sec)
第10章 创建可计算字段
拼接字段
mysql> select Concat(vend_name, ' (', vend_country, ')') from vendors order by vend_name;
+--------------------------------------------+
| Concat(vend_name, ' (', vend_country, ')') |
+--------------------------------------------+
| ACME (USA) |
| Anvils R Us (USA) |
| Furball Inc. (USA) |
| Jet Set (England) |
| Jouets Et Ours (France) |
| LT Supplies (USA) |
+--------------------------------------------+
6 rows in set (0.00 sec)
# Trim函数 MySQL除了支持RTrim()（正如刚才所见，它去掉
# 串右边的空格），还支持LTrim()（去掉串左边的空格）以及
# Trim()（去掉串左右两边的空格）。
使用别名
mysql> select Concat(vend_name, ' (', vend_country, ')') as vend_title from vendors order by vend_name;
+-------------------------+
| vend_title |
+-------------------------+
| ACME (USA) |
| Anvils R Us (USA) |
| Furball Inc. (USA) |
| Jet Set (England) |
| Jouets Et Ours (France) |
| LT Supplies (USA) |
+-------------------------+
6 rows in set (0.00 sec)
执行算数计算
mysql> select prod_id, quantity, item_price, quantity*item_price as expanded_price from orderitems where order_num='20005';
+---------+----------+------------+----------------+
| prod_id | quantity | item_price | expanded_price |
+---------+----------+------------+----------------+
| ANV01 | 10 | 5.99 | 59.90 |
| ANV02 | 3 | 9.99 | 29.97 |
| TNT2 | 5 | 10.00 | 50.00 |
| FB | 1 | 10.00 | 10.00 |
+---------+----------+------------+----------------+
4 rows in set (0.00 sec)
第11章 使用数据处理函数
文本处理函数
mysql> select prod_name, Upper(prod_name), prod_price from products where prod_name regexp '.000';
+--------------+------------------+------------+
| prod_name | Upper(prod_name) | prod_price |
+--------------+------------------+------------+
| JetPack 1000 | JETPACK 1000 | 35.00 |
| JetPack 2000 | JETPACK 2000 | 55.00 |
+--------------+------------------+------------+
2 rows in set (0.00 sec)
日期和时间处理函数
mysql> select order_date, cust_id from orders where Date(order_date) = '2005-09-01';
+---------------------+---------+
| order_date | cust_id |
+---------------------+---------+
| 2005-09-01 00:00:00 | 10001 |
+---------------------+---------+
1 row in set (0.00 sec)
mysql> select order_date, cust_id from orders where Year(order_date) = '2005' and Month(order_date) = '09';
+---------------------+---------+
| order_date | cust_id |
+---------------------+---------+
| 2005-09-01 00:00:00 | 10001 |
| 2005-09-12 00:00:00 | 10003 |
| 2005-09-30 00:00:00 | 10004 |
+---------------------+---------+
3 rows in set (0.00 sec)
数值处理函数
第12章 汇总数据
聚集函数
AVG()
mysql> select AVG(prod_price) as avg_price from products;
+-----------+
| avg_price |
+-----------+
| 16.133571 |
+-----------+
1 row in set (0.01 sec)
mysql> select AVG(prod_price) as avg_price from products where vend_id = '1003';
+-----------+
| avg_price |
+-----------+
| 13.212857 |
+-----------+
1 row in set (0.01 sec)
COUNT()
mysql> select COUNT(*) as num_cust from customers;
+----------+
| num_cust |
+----------+
| 5 |
+----------+
1 row in set (0.00 sec)
mysql> select COUNT(cust_email) as num_cust from customers;
+----------+
| num_cust |
+----------+
| 3 |
+----------+
1 row in set (0.00 sec)
MAX()
mysql> select MAX(prod_price) as max_price from products;
+-----------+
| max_price |
+-----------+
| 55.00 |
+-----------+
1 row in set (0.00 sec)
MIN()
mysql> select MIN(prod_price) as max_price from products;
+-----------+
| max_price |
+-----------+
| 2.50 |
+-----------+
1 row in set (0.00 sec)
SUM()
mysql> select SUM(quantity) as ieems_orders from orderitems where order_num = '20005';
+--------------+
| ieems_orders |
+--------------+
| 19 |
+--------------+
1 row in set (0.00 sec)
聚集不同值
以上5个聚集函数都可以如下使用：
对所有的行执行计算，指定ALL参数或不给参数（因为ALL是默认
行为）；
只包含不同的值，指定DISTINCT参数。
mysql> select AVG(distinct prod_price) as avg_price from products where vend_id = '1003';
+-----------+
| avg_price |
+-----------+
| 15.998000 |
+-----------+
1 row in set (0.00 sec)
组合聚集函数
mysql> select COUNT(*) as num_items, MIN(prod_price) as min_price, MAX(prod_price) as max_price, AVG(prod_price) as avg_price from products;
+-----------+-----------+-----------+-----------+
| num_items | min_price | max_price | avg_price |
+-----------+-----------+-----------+-----------+
| 14 | 2.50 | 55.00 | 16.133571 |
+-----------+-----------+-----------+-----------+
1 row in set (0.00 sec)
第13章 分组数据
mysql> select vend_id, COUNT(*) as num_prods from products group by vend_id;
+---------+-----------+
| vend_id | num_prods |
+---------+-----------+
| 1001 | 3 |
| 1002 | 2 |
| 1003 | 7 |
| 1005 | 2 |
+---------+-----------+
4 rows in set (0.00 sec)
mysql> select vend_id, COUNT(*) as num_prods from products group by vend_id with rollup;
+---------+-----------+
| vend_id | num_prods |
+---------+-----------+
| 1001 | 3 |
| 1002 | 2 |
| 1003 | 7 |
| 1005 | 2 |
| NULL | 14 |
+---------+-----------+
5 rows in set (0.00 sec)
在具体使用GROUP BY子句前，需要知道一些重要的规定。
GROUP BY子句可以包含任意数目的列。这使得能对分组进行嵌套，
为数据分组提供更细致的控制。
如果在GROUP BY子句中嵌套了分组，数据将在最后规定的分组上
进行汇总。换句话说，在建立分组时，指定的所有列都一起计算
（所以不能从个别的列取回数据）。
GROUP BY子句中列出的每个列都必须是检索列或有效的表达式
（但不能是聚集函数）。如果在SELECT中使用表达式，则必须在
GROUP BY子句中指定相同的表达式。不能使用别名。
除聚集计算语句外， SELECT语句中的每个列都必须在GROUP BY子
句中给出。
如果分组列中具有NULL值，则NULL将作为一个分组返回。如果列
中有多行NULL值，它们将分为一组 。
GROUP BY子句必须出现在WHERE子句之后， ORDER BY子句之前 。
过滤分组
mysql> select vend_id, COUNT(*) as num_prods from products group by vend_id having COUNT(*) >=3;
+---------+-----------+
| vend_id | num_prods |
+---------+-----------+
| 1001 | 3 |
| 1003 | 7 |
+---------+-----------+
2 rows in set (0.00 sec)
mysql> select vend_id, COUNT(*) as num_prods from products where prod_price >= 10 group by vend_id having COUNT(*) >=2;
+---------+-----------+
| vend_id | num_prods |
+---------+-----------+
| 1003 | 4 |
| 1005 | 2 |
+---------+-----------+
2 rows in set (0.00 sec)
mysql> select order_num, SUM(quantity*item_price) as ordertotal
-> from orderitems
-> group by order_num
-> having SUM(quantity*item_price) >= 50;
+-----------+------------+
| order_num | ordertotal |
+-----------+------------+
| 20005 | 149.87 |
| 20006 | 55.00 |
| 20007 | 1000.00 |
| 20008 | 125.00 |
+-----------+------------+
4 rows in set (0.00 sec)
mysql> select order_num, SUM(quantity*item_price) as ordertotal
-> from orderitems
-> group by order_num
-> having SUM(quantity*item_price) >= 50
-> order by ordertotal;
+-----------+------------+
| order_num | ordertotal |
+-----------+------------+
| 20006 | 55.00 |
| 20008 | 125.00 |
| 20005 | 149.87 |
| 20007 | 1000.00 |
+-----------+------------+
4 rows in set (0.00 sec)
select子句顺序
第14章 使用子查询
利用子查询进行过滤
mysql> select cust_id from orders where order_num in (select order_num from orderitems where prod_id = 'TNT2');
+---------+
| cust_id |
+---------+
| 10001 |
| 10004 |
+---------+
2 rows in set (0.00 sec)
mysql> select cust_id, cust_contact
-> from customers
-> where cust_id in (
-> select cust_id from orders where order_num in (
-> select order_num from orderitems where prod_id = 'TNT2'));
+---------+--------------+
| cust_id | cust_contact |
+---------+--------------+
| 10001 | Y Lee |
| 10004 | Y Sam |
+---------+--------------+
2 rows in set (0.00 sec)
(1) 从customers表中检索客户列表。
(2) 对于检索出的每个客户，统计其在orders表中的订单数目。
mysql> select cust_name,
-> cust_state,
-> (select COUNT(*)
-> from orders
-> where orders.cust_id = customers.cust_id) as orders
-> from customers
-> order by cust_name;
+----------------+------------+--------+
| cust_name | cust_state | orders |
+----------------+------------+--------+
| Coyote Inc. | MI | 2 |
| E Fudd | IL | 1 |
| Mouse House | OH | 0 |
| Wascals | IN | 1 |
| Yosemite Place | AZ | 1 |
+----------------+------------+--------+
5 rows in set (0.00 sec)
第15章 联结表
创建联结
mysql> select vend_name, prod_id, prod_price
-> from vendors, products
-> where vendors.vend_id = products.vend_id
-> order by vend_name, prod_name;
+-------------+---------+------------+
| vend_name | prod_id | prod_price |
+-------------+---------+------------+
| ACME | FB | 10.00 |
| ACME | FC | 2.50 |
| ACME | DTNTR | 13.00 |
| ACME | SAFE | 50.00 |
| ACME | SLING | 4.49 |
| ACME | TNT1 | 2.50 |
| ACME | TNT2 | 10.00 |
| Anvils R Us | ANV01 | 5.99 |
| Anvils R Us | ANV02 | 9.99 |
| Anvils R Us | ANV03 | 14.99 |
| Jet Set | JP1000 | 35.00 |
| Jet Set | JP2000 | 55.00 |
| LT Supplies | FU1 | 3.42 |
| LT Supplies | OL1 | 8.99 |
+-------------+---------+------------+
14 rows in set (0.00 sec)
mysql> select vend_name, prod_id, prod_price
-> from vendors inner join products
-> on vendors.vend_id = products.vend_id
-> order by vend_name, prod_name;
+-------------+---------+------------+
| vend_name | prod_id | prod_price |
+-------------+---------+------------+
| ACME | FB | 10.00 |
| ACME | FC | 2.50 |
| ACME | DTNTR | 13.00 |
| ACME | SAFE | 50.00 |
| ACME | SLING | 4.49 |
| ACME | TNT1 | 2.50 |
| ACME | TNT2 | 10.00 |
| Anvils R Us | ANV01 | 5.99 |
| Anvils R Us | ANV02 | 9.99 |
| Anvils R Us | ANV03 | 14.99 |
| Jet Set | JP1000 | 35.00 |
| Jet Set | JP2000 | 55.00 |
| LT Supplies | FU1 | 3.42 |
| LT Supplies | OL1 | 8.99 |
+-------------+---------+------------+
14 rows in set (0.00 sec)
mysql> select cust_name, cust_contact
-> from customers, orders, orderitems
-> where customers.cust_id = orders.cust_id
-> and orders.order_num = orderitems.order_num
-> and prod_id = 'TNT2';
+----------------+--------------+
| cust_name | cust_contact |
+----------------+--------------+
| Coyote Inc. | Y Lee |
| Yosemite Place | Y Sam |
+----------------+--------------+
2 rows in set (0.00 sec)
第16章 创建高级联结
使用表别名
# 使用列别名
mysql> select Concat(RTrim(vend_name), ' (', RTrim(vend_country), ')') as
-> vend_title
-> from vendors
-> order by vend_name;
+-------------------------+
| vend_title |
+-------------------------+
| ACME (USA) |
| Anvils R Us (USA) |
| Furball Inc. (USA) |
| Jet Set (England) |
| Jouets Et Ours (France) |
| LT Supplies (USA) |
+-------------------------+
6 rows in set (0.00 sec)
# 使用表别名
mysql> select cust_name, cust_contact
-> from customers as c, orders as o, orderitems as oi
-> where c.cust_id = o.cust_id
-> and oi.order_num = o.order_num
-> and prod_id = 'TNT2';
+----------------+--------------+
| cust_name | cust_contact |
+----------------+--------------+
| Coyote Inc. | Y Lee |
| Yosemite Place | Y Sam |
+----------------+--------------+
2 rows in set (0.00 sec)
使用不同的联结
自联结
假如你发现某物品（其ID为DTNTR）存在问题，因此想知道生产该物
品的供应商生产的其他物品是否也存在这些问题。此查询要求首先找到
生产ID为DTNTR的物品的供应商，然后找出这个供应商生产的其他物品。
# 使用子查询
mysql> select prod_id, prod_name
-> from products
-> where vend_id = (select vend_id
-> from products
-> where prod_id = 'DTNTR');
+---------+----------------+
| prod_id | prod_name |
+---------+----------------+
| DTNTR | Detonator |
| FB | Bird seed |
| FC | Carrots |
| SAFE | Safe |
| SLING | Sling |
| TNT1 | TNT (1 stick) |
| TNT2 | TNT (5 sticks) |
+---------+----------------+
7 rows in set (0.00 sec)
# 使用自联结
mysql> select p1.prod_id, p1.prod_name
-> from products as p1, products as p2
-> where p1.vend_id = p2.vend_id
-> and p2.prod_id = 'DTNTR';
+---------+----------------+
| prod_id | prod_name |
+---------+----------------+
| DTNTR | Detonator |
| FB | Bird seed |
| FC | Carrots |
| SAFE | Safe |
| SLING | Sling |
| TNT1 | TNT (1 stick) |
| TNT2 | TNT (5 sticks) |
+---------+----------------+
7 rows in set (0.00 sec)
自然联结
mysql> select c.*, o.order_num, o.order_date, oi.prod_id, oi.quantity, oi.item_price
-> from customers as c, orders as o, orderitems as oi
-> where c.cust_id = o.cust_id
-> and oi.order_num = o.order_num
-> and oi.prod_id = 'FB';
+---------+-------------+----------------+-----------+------------+----------+--------------+--------------+-----------------+-----------+---------------------+---------+----------+------------+
| cust_id | cust_name | cust_address | cust_city | cust_state | cust_zip | cust_country | cust_contact | cust_email
| order_num | order_date | prod_id | quantity | item_price |
+---------+-------------+----------------+-----------+------------+----------+--------------+--------------+-----------------+-----------+---------------------+---------+----------+------------+
| 10001 | Coyote Inc. | 200 Maple Lane | Detroit | MI | 44444 | USA | Y Lee | ylee@coyote.com | 20005 | 2005-09-01 00:00:00 | FB | 1 | 10.00 |
| 10001 | Coyote Inc. | 200 Maple Lane | Detroit | MI | 44444 | USA | Y Lee | ylee@coyote.com | 20009 | 2005-10-08 00:00:00 | FB | 1 | 10.00 |
+---------+-------------+----------------+-----------+------------+----------+--------------+--------------+-----------------+-----------+---------------------+---------+----------+------------+
2 rows in set (0.00 sec)
外部联结
# 内连接
# 检索所有客户及其订单
mysql> select customers.cust_id, orders.order_num
-> from customers inner join orders
-> on customers.cust_id = orders.cust_id;
+---------+-----------+
| cust_id | order_num |
+---------+-----------+
| 10001 | 20005 |
| 10001 | 20009 |
| 10003 | 20006 |
| 10004 | 20007 |
| 10005 | 20008 |
+---------+-----------+
5 rows in set (0.00 sec)
# 外部联结
# 包含那些没有订单的客户
mysql> select customers.cust_id, orders.order_num
-> from customers left outer join orders
-> on customers.cust_id = orders.cust_id;
+---------+-----------+
| cust_id | order_num |
+---------+-----------+
| 10001 | 20005 |
| 10001 | 20009 |
| 10002 | NULL |
| 10003 | 20006 |
| 10004 | 20007 |
| 10005 | 20008 |
+---------+-----------+
6 rows in set (0.00 sec)
使用带聚集函数的联结
# 检索所有客户及每个客户所下的订单数
mysql> select customers.cust_name, customers.cust_id, COUNT(orders.order_num) as num_ord
-> from customers inner join orders
-> on customers.cust_id = orders.cust_id
-> group by customers.cust_id;
+----------------+---------+---------+
| cust_name | cust_id | num_ord |
+----------------+---------+---------+
| Coyote Inc. | 10001 | 2 |
| Wascals | 10003 | 1 |
| Yosemite Place | 10004 | 1 |
| E Fudd | 10005 | 1 |
+----------------+---------+---------+
4 rows in set (0.00 sec)
# 包含没有任何订单的客户
mysql> select customers.cust_name, customers.cust_id, COUNT(orders.order_num) as num_ord
-> from customers left outer join orders
-> on customers.cust_id = orders.cust_id
-> group by customers.cust_id;
+----------------+---------+---------+
| cust_name | cust_id | num_ord |
+----------------+---------+---------+
| Coyote Inc. | 10001 | 2 |
| Mouse House | 10002 | 0 |
| Wascals | 10003 | 1 |
| Yosemite Place | 10004 | 1 |
| E Fudd | 10005 | 1 |
+----------------+---------+---------+
5 rows in set (0.00 sec)
使用联结和联结的条件
在总结关于联结的这两章前，有必要汇总一下关于联结及其使用的
某些要点。
注意所使用的联结类型。一般我们使用内部联结，但使用外部联
结也是有效的。
保证使用正确的联结条件，否则将返回不正确的数据。
应该总是提供联结条件，否则会得出笛卡儿积。
在一个联结中可以包含多个表，甚至对于每个联结可以采用不同
的联结类型。虽然这样做是合法的，一般也很有用，但应该在一
起测试它们前，分别测试每个联结。这将使故障排除更为简单。
第17章 组合查询
创建组合查询
# where查询
mysql> select vend_id, prod_id, prod_price
-> from products
-> where prod_price <= 5 or vend_id in (1001, 1002);
+---------+---------+------------+
| vend_id | prod_id | prod_price |
+---------+---------+------------+
| 1001 | ANV01 | 5.99 |
| 1001 | ANV02 | 9.99 |
| 1001 | ANV03 | 14.99 |
| 1003 | FC | 2.50 |
| 1002 | FU1 | 3.42 |
| 1002 | OL1 | 8.99 |
| 1003 | SLING | 4.49 |
| 1003 | TNT1 | 2.50 |
+---------+---------+------------+
8 rows in set (0.00 sec)
# union
mysql> select vend_id, prod_id, prod_price
-> from products
-> where prod_price <= 5
-> union
-> select vend_id, prod_id, prod_price
-> from products
-> where vend_id in (1001, 1002);
+---------+---------+------------+
| vend_id | prod_id | prod_price |
+---------+---------+------------+
| 1003 | FC | 2.50 |
| 1002 | FU1 | 3.42 |
| 1003 | SLING | 4.49 |
| 1003 | TNT1 | 2.50 |
| 1001 | ANV01 | 5.99 |
| 1001 | ANV02 | 9.99 |
| 1001 | ANV03 | 14.99 |
| 1002 | OL1 | 8.99 |
+---------+---------+------------+
8 rows in set (0.00 sec)
UNION与WHERE 本章开始时说过，UNION几乎总是完成与多个
WHERE条件相同的工作。UNION ALL为UNION的一种形式，它完成
WHERE子句完成不了的工作。如果确实需要每个条件的匹配行全
部出现（包括重复行），则必须使用UNION ALL而不是WHERE。
# 排序union查询
mysql> select vend_id, prod_id, prod_price
-> from products
-> where prod_price <= 5
-> union
-> select vend_id, prod_id, prod_price
-> from products
-> where vend_id in (1001, 1002)
-> order by vend_id, prod_price;
+---------+---------+------------+
| vend_id | prod_id | prod_price |
+---------+---------+------------+
| 1001 | ANV01 | 5.99 |
| 1001 | ANV02 | 9.99 |
| 1001 | ANV03 | 14.99 |
| 1002 | FU1 | 3.42 |
| 1002 | OL1 | 8.99 |
| 1003 | FC | 2.50 |
| 1003 | TNT1 | 2.50 |
| 1003 | SLING | 4.49 |
+---------+---------+------------+
8 rows in set (0.00 sec)
第18章 全文本搜索
使用全文本搜索
进行全文本搜索
mysql> select note_text
-> from productnotes
-> where Match(note_text) Against('rabbit');
+-----------------------------------------------------------------------------------------------------------------------+
| note_text
|
+-----------------------------------------------------------------------------------------------------------------------+
| Customer complaint: rabbit has been able to detect trap, food apparently less effective now.
|
| Quantity varies, sold by the sack load.
All guaranteed to be bright and orange, and suitable for use as rabbit bait. |
+-----------------------------------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)
mysql> select note_text, Match(note_text) Against('rabbit') as rank
-> from productnotes;
使用查询扩展
# 未使用查询扩展
mysql> select note_text
-> from productnotes
-> where Match(note_text) Against('anvils');
+----------------------------------------------------------------------------------------------------------------------------------------------------------+
| note_text
|
+----------------------------------------------------------------------------------------------------------------------------------------------------------+
| Multiple customer returns, anvils failing to drop fast enough or falling backwards on purchaser. Recommend that customer considers using heavier anvils. |
+----------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
# 使用扩展
mysql> select note_text
-> from productnotes
-> where Match(note_text) Against('anvils' with query expansion);
+----------------------------------------------------------------------------------------------------------------------------------------------------------+
| note_text
|
+----------------------------------------------------------------------------------------------------------------------------------------------------------+
| Multiple customer returns, anvils failing to drop fast enough or falling backwards on purchaser. Recommend that customer considers using heavier anvils. |
| Customer complaint:
Sticks not individually wrapped, too easy to mistakenly detonate all at once.
Recommend individual wrapping. |
| Customer complaint:
Not heavy enough to generate flying stars around head of victim. If being purchased for dropping, recommend ANV02 or ANV03 instead. |
| Please note that no returns will be accepted if safe opened using explosives.
|
| Customer complaint: rabbit has been able to detect trap, food apparently less effective now.
|
| Customer complaint:
Circular hole in safe floor can apparently be easily cut with handsaw.
|
| Matches not included, recommend purchase of matches or detonator (item DTNTR).
|
+----------------------------------------------------------------------------------------------------------------------------------------------------------+
7 rows in set (0.00 sec)
这次返回了7行。第一行包含词anvils，因此等级最高。第二
行与anvils无关，但因为它包含第一行中的两个词（customer
和recommend），所以也被检索出来。第3行也包含这两个相同的词，但它
们在文本中的位置更靠后且分开得更远，因此也包含这一行，但等级为
第三。第三行确实也没有涉及anvils（按它们的产品名）。
第19章 插入数据
插入完整的行
mysql> insert into customers
values(null, 'Prp E. LaPew', '100 Main Street', 'Los Angeles', 'CA', '90046', 'USA',null, null);
Query OK, 1 row affected (0.06 sec)
insert更安全的写法
mysql> insert into customers(cust_name,
-> cust_address,
-> cust_city,
-> cust_state,
-> cust_zip,
-> cust_country,
-> cust_contact,
-> cust_email)
-> values('Pep E. LaPew',
-> '100 main street',
-> 'Los Angeles',
-> 'CA',
-> '90046',
-> 'USA',
-> null,
-> null);
Query OK, 1 row affected (0.04 sec)
插入多个行
其中单条INSERT语句有多组值，每组值用一对圆括号括起来，
用逗号分隔。
插入检索出的数据
insert select
第20章 更新和删除数据
更新数据
# id为10005的顾客增加Email
mysql> update customers
-> set cust_email = 'emler@fudd.com'
-> where cust_id = '10005';
Query OK, 1 row affected (0.03 sec)
Rows matched: 1 Changed: 1 Warnings: 0
删除数据
mysql> delete from customers
-> where cust_id = '10006';
Query OK, 1 row affected (0.04 sec)
**更快的删除 如果想从表中删除所有行，不要使用DELETE。 **
可使用TRUNCATE TABLE语句，它完成相同的工作，但速度更
快（TRUNCATE实际是删除原来的表并重新创建一个表，而不
是逐行删除表中的数据）。
**下面是许多SQL程序员使用UPDATE或DELETE时所遵循的习惯。 **
除非确实打算更新和删除每一行，否则绝对不要使用不带WHERE
子句的UPDATE或DELETE语句。
保证每个表都有主键（如果忘记这个内容，请参阅第15章），尽可能
像WHERE子句那样使用它（可以指定各主键、多个值或值的范围）。
在对UPDATE或DELETE语句使用WHERE子句前，应该先用SELECT进
行测试，保证它过滤的是正确的记录，以防编写的WHERE子句不
正确。
使用强制实施引用完整性的数据库（关于这个内容，请参阅第15
章），这样MySQL将不允许删除具有与其他表相关联的数据的行。
第21章 创建和操纵表
第22章 使用视图
利用视图简化复杂的联结
mysql> create view productcustomers as
-> select cust_name, cust_contact, prod_id
-> from customers, orders, orderitems
-> where customers.cust_id = orders.cust_id
-> and orderitems.order_num = orders.order_num;
Query OK, 0 rows affected (0.03 sec)
mysql> select * from productcustomers;
+----------------+--------------+---------+
| cust_name | cust_contact | prod_id |
+----------------+--------------+---------+
| Coyote Inc. | Y Lee | ANV01 |
| Coyote Inc. | Y Lee | ANV02 |
| Coyote Inc. | Y Lee | TNT2 |
| Coyote Inc. | Y Lee | FB |
| Coyote Inc. | Y Lee | FB |
| Coyote Inc. | Y Lee | OL1 |
| Coyote Inc. | Y Lee | SLING |
| Coyote Inc. | Y Lee | ANV03 |
| Wascals | Jim Jones | JP2000 |
| Yosemite Place | Y Sam | TNT2 |
| E Fudd | E Fudd | FC |
+----------------+--------------+---------+
11 rows in set (0.00 sec)
用视图重新格式化检索出的数据
mysql> create view vendorlocations as
-> select Concat(RTrim(vend_name), ' (', RTrim(vend_country), ')') as vend_title
-> from vendors
-> order by vend_name;
Query OK, 0 rows affected (0.03 sec)
mysql> select * from vendorlocations;
+-------------------------+
| vend_title |
+-------------------------+
| ACME (USA) |
| Anvils R Us (USA) |
| Furball Inc. (USA) |
| Jet Set (England) |
| Jouets Et Ours (France) |
| LT Supplies (USA) |
+-------------------------+
6 rows in set (0.00 sec)
用视图过滤不想要的数据
mysql> create view customeremaillist as
-> select cust_id, cust_name, cust_email
-> from customers
-> where cust_email is not null;
Query OK, 0 rows affected (0.03 sec)
mysql> select * from customeremaillist;
+---------+----------------+---------------------+
| cust_id | cust_name | cust_email |
+---------+----------------+---------------------+
| 10001 | Coyote Inc. | ylee@coyote.com |
| 10003 | Wascals | rabbit@wascally.com |
| 10004 | Yosemite Place | sam@yosemite.com |
| 10005 | E Fudd | emler@fudd.com |
+---------+----------------+---------------------+
4 rows in set (0.00 sec)
使用视图与计算字段
mysql> create view orderitemsexpanded as
-> select order_num, prod_id, quantity, item_price, quantity*item_price as expanded_price
-> from orderitems;
Query OK, 0 rows affected (0.02 sec)
mysql> select * from orderitemsexpanded
-> where order_num = '20005';
+-----------+---------+----------+------------+----------------+
| order_num | prod_id | quantity | item_price | expanded_price |
+-----------+---------+----------+------------+----------------+
| 20005 | ANV01 | 10 | 5.99 | 59.90 |
| 20005 | ANV02 | 3 | 9.99 | 29.97 |
| 20005 | TNT2 | 5 | 10.00 | 50.00 |
| 20005 | FB | 1 | 10.00 | 10.00 |
+-----------+---------+----------+------------+----------------+
4 rows in set (0.00 sec)
第23章 使用存储过程
创建存储过程
# 在客户端执行切换分隔符
mysql> delimiter //
mysql> create procedure productpricing(
-> out pl decimal(8,2),
-> out ph decimal(8,2),
-> out pa decimal(8,2))
-> begin
-> select Min(prod_price)
-> into pl
-> from products;
-> select Max(prod_price)
-> into ph
-> from products;
-> select Avg(prod_price)
-> into pa
-> from products;
-> end//
Query OK, 0 rows affected (0.00 sec)
mysql> delimiter ;
mysql> call productpricing(@pricelow, @pricehigh, @priceavg);
Query OK, 1 row affected, 1 warning (0.00 sec)
mysql> select @pricelow, @pricehigh, @priceavg;
+-----------+------------+-----------+
| @pricelow | @pricehigh | @priceavg |
+-----------+------------+-----------+
| 2.50 | 55.00 | 16.13 |
+-----------+------------+-----------+
1 row in set (0.00 sec)
第24章 使用游标
第25章 使用触发器
创建触发器
mysql> create trigger newproduct after insert on products
-> for each row select 'Product added' into @ee;
Query OK, 0 rows affected (0.06 sec)
mysql> select @ee;
+------+
| @ee |
+------+
| NULL |
+------+
1 row in set (0.00 sec)
mysql> desc products;
+------------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------+--------------+------+-----+---------+-------+
| prod_id | char(10) | NO | PRI | NULL | |
| vend_id | int(11) | NO | MUL | NULL | |
| prod_name | char(255) | NO | | NULL | |
| prod_price | decimal(8,2) | NO | | NULL | |
| prod_desc | text | YES | | NULL | |
+------------+--------------+------+-----+---------+-------+
5 rows in set (0.01 sec)
mysql> insert products(prod_id, vend_id, prod_name, prod_price)
-> values('20009', '1002', 'ysxu', 2.56);
Query OK, 1 row affected (0.04 sec)
mysql> select @ee;
+---------------+
| @ee |
+---------------+
| Product added |
+---------------+
1 row in set (0.00 sec)
第26章 管理事务处理
第28章 安全管理
管理用户
创建用户账号
create user [用户名] identified by [用户密码]
用户重命名
rename user [旧用户名] to [新用户名]
删除用户账号
drop user [用户名]
设置访问权限
# 查看用户的权限
show grants for [用户名] //完整用户名：'用户名'@'主机'
# 设置访问权限
grant all on *.* to [用户名]
all-所有权限
*.*-所有数据库下所有表
#grant的反操作是revoke
更改密码
set password for [用户名] = Password('密码')
# 设置当前用户的密码
set password = Passwprd('密码')