MySQL Tutorial(2)
MySQL Tutorial(2)
目前的情况是一边学Java，一边学习MySQL。看的是MySQL提供的文档，这篇博文是学习的总结。（2016-4-6）
本文最后更新时间：2016-4-7
NOTE：MySQL Tutorial(1)在这里
3.5：在批处理模式下使用mysql
1：批处理模式下mysql的使用方法（这个方法可能在windows下行不通）
Step 1：将mysql的查询语句写在一个文本文件里，假设文本文件名为batch-file.txt
Step 2：在命令行下使用`mysql < batch batch-file.txt
注意：Step 2并没有说清楚。总结来说，要让MySQL运行批处理脚本分为两种情况。
第一种是在你没有登陆MySQL Service的情况下。这时候你可以在登陆命令的后面接上`` < batch-file.txt。注意，你必须在登陆命令中指定要登录的数据库，如果不指定，那你要人家对哪个数据库进行操作呢。一个例子如下：
wallace@zhenghong-E430:~$ mysql -u root -p test < batch-file.txt
Enter password:
name owner species sex birth death
Fluffy Harold cat f 1993-02-04 NULL
Claws Gwen cat m 1994-03-17 NULL
Buffy Harold dog f 1989-05-13 NULL
Fang Benny dog m 1990-08-27 NULL
Bowser Diane dog m 1989-08-31 1995-07-29
Chirpy Gwen bird f 1998-09-11 NULL
Whistl Gwen bird NULL 1997-12-09 NULL
Slim Benny snake m 1996-04-29 NULL
Puff Diane hamster f 1999-03-30 NULL
wallace@zhenghong-E430:~$ 第二种是在你已经登陆了的情况。这时你可以使用source batch-file.txt命令或者\. batch-file.txt来执行批处理文件batch-file.txt
mysql> source batch-file.txt
+--------+--------+---------+------+------------+------------+
| name | owner | species | sex | birth | death |
+--------+--------+---------+------+------------+------------+
| Fluffy | Harold | cat | f | 1993-02-04 | NULL |
| Claws | Gwen | cat | m | 1994-03-17 | NULL |
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
| Fang | Benny | dog | m | 1990-08-27 | NULL |
| Bowser | Diane | dog | m | 1989-08-31 | 1995-07-29 |
| Chirpy | Gwen | bird | f | 1998-09-11 | NULL |
| Whistl | Gwen | bird | NULL | 1997-12-09 | NULL |
| Slim | Benny | snake | m | 1996-04-29 | NULL |
| Puff | Diane | hamster | f | 1999-03-30 | NULL |
+--------+--------+---------+------+------------+------------+
9 rows in set (0.00 sec)
mysql> mysql> \. batch-file.txt
+--------+--------+---------+------+------------+------------+
| name | owner | species | sex | birth | death |
+--------+--------+---------+------+------------+------------+
| Fluffy | Harold | cat | f | 1993-02-04 | NULL |
| Claws | Gwen | cat | m | 1994-03-17 | NULL |
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
| Fang | Benny | dog | m | 1990-08-27 | NULL |
| Bowser | Diane | dog | m | 1989-08-31 | 1995-07-29 |
| Chirpy | Gwen | bird | f | 1998-09-11 | NULL |
| Whistl | Gwen | bird | NULL | 1997-12-09 | NULL |
| Slim | Benny | snake | m | 1996-04-29 | NULL |
| Puff | Diane | hamster | f | 1999-03-30 | NULL |
+--------+--------+---------+------+------------+------------+
9 rows in set (0.00 sec)
mysql> 2：If you want the script to continue even if some of the statements in it produce errors, you should use the –force command-line option.
3：从上面可以看到，在batch mode和在命令行下输出是不一样的。batch mode下的输出少了分隔符。使用-t选项来使得batch mode下的输出格式和命令行下的一样
wallace@zhenghong-E430:~$ mysql -t -u root -p test < batch-file.txt
Enter password:
+--------+--------+---------+------+------------+------------+
| name | owner | species | sex | birth | death |
+--------+--------+---------+------+------------+------------+
| Fluffy | Harold | cat | f | 1993-02-04 | NULL |
| Claws | Gwen | cat | m | 1994-03-17 | NULL |
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
| Fang | Benny | dog | m | 1990-08-27 | NULL |
| Bowser | Diane | dog | m | 1989-08-31 | 1995-07-29 |
| Chirpy | Gwen | bird | f | 1998-09-11 | NULL |
| Whistl | Gwen | bird | NULL | 1997-12-09 | NULL |
| Slim | Benny | snake | m | 1996-04-29 | NULL |
| Puff | Diane | hamster | f | 1999-03-30 | NULL |
+--------+--------+---------+------+------------+------------+
wallace@zhenghong-E430:~$ 3.6：常见查询的例子
1：在test数据库中新建shop表格并插入以下数据
CREATE TABLE shop ( article INT(4) UNSIGNED ZEROFILL DEFAULT '0000' NOT NULL, dealer CHAR(20) DEFAULT '' NOT NULL, price DOUBLE(16,2) DEFAULT '0.00' NOT NULL, PRIMARY KEY(article, dealer));mysql> INSERT INTO shop VALUES
-> (1, 'A', 3.45), -> (1, 'B', 3.99), -> (2, 'A', 10.99), -> (3, 'B', 1.45), -> (3, 'C', 1.69), -> (3, 'D', 1.25), -> (4, 'D', 19.95) ; Query OK, 7 rows affected (0.06 sec)
Records: 7 Duplicates: 0 Warnings: 0
mysql>
mysql> SELECT * FROM shop; +---------+--------+-------+
| article | dealer | price | +---------+--------+-------+
| 0001 | A | 3.45 |
| 0001 | B | 3.99 |
| 0002 | A | 10.99 |
| 0003 | B | 1.45 |
| 0003 | C | 1.69 |
| 0003 | D | 1.25 |
| 0004 | D | 19.95 | +---------+--------+-------+
7 rows in set (0.00 sec)
mysql> 2：求某一列的最大值（这里就是看书的最大编号是多少）
mysql> SELECT MAX(article) AS MaxArticle FROM shop; +------------+
| MaxArticle | +------------+
| 4 | +------------+
1 row in set (0.02 sec)
mysql> 3：找出价格最高的那一整行
mysql> SELECT * FROM shop
-> WHERE price = (SELECT MAX(price) FROM shop) ; +---------+--------+-------+
| article | dealer | price | +---------+--------+-------+
| 0004 | D | 19.95 | +---------+--------+-------+
1 row in set (0.02 sec)
mysql> 其实对于这个任务还有其他的几个方法，不过那几个方法目前看起来太难了。暂时先略过。以后遇到了必须用其他方法时再来
4：找出每组当中最大的某些列（得用GROUP BY分组）
任务：找出每一个article中最大的价格
mysql> SELECT article, MAX(price) AS price
-> FROM shop
-> GROUP BY article; +---------+-------+
| article | price | +---------+-------+
| 0001 | 3.99 |
| 0002 | 10.99 |
| 0003 | 1.69 |
| 0004 | 19.95 | +---------+-------+
4 rows in set (0.02 sec)
mysql> 5：对于每一个article，找到它的dealer或者是要价最高的dealer
mysql> SELECT article, dealer, price
-> FROM shop s1
-> WHERE price = (
-> SELECT MAX(s2.price)
-> FROM shop s2
-> WHERE s1.article = s2.article)
-> ; +---------+--------+-------+
| article | dealer | price | +---------+--------+-------+
| 0001 | B | 3.99 |
| 0002 | A | 10.99 |
| 0003 | C | 1.69 |
| 0004 | D | 19.95 | +---------+--------+-------+
4 rows in set (0.03 sec)
mysql> 其他实现方法
mysql> SELECT s1.article, dealer, s1.price FROM shop s1 JOIN ( SELECT article, MAX(price) AS price FROM shop GROUP BY article) AS s2 ON s1.article = s2.article AND s1.price = s2.price; +---------+--------+-------+
| article | dealer | price | +---------+--------+-------+
| 0001 | B | 3.99 |
| 0002 | A | 10.99 |
| 0003 | C | 1.69 |
| 0004 | D | 19.95 | +---------+--------+-------+
4 rows in set (0.00 sec)
mysql> mysql> SELECT s1.article, s1.dealer, s1.price FROM shop s1 LEFT JOIN shop s2 ON s1.article = s2.article AND s1.price < s2.price WHERE s2.article IS NULL; +---------+--------+-------+
| article | dealer | price | +---------+--------+-------+
| 0001 | B | 3.99 |
| 0002 | A | 10.99 |
| 0003 | C | 1.69 |
| 0004 | D | 19.95 | +---------+--------+-------+
4 rows in set (0.03 sec)
mysql> 7：使用用户自定义的变量（这里只提供了一个简单的例子）
任务：找到有最低和最高价格的article和price
mysql> SELECT @min_price:=MIN(price), @max_price:=MAX(price) FROM shop; +------------------------+------------------------+
| @min_price:=MIN(price) | @max_price:=MAX(price) | +------------------------+------------------------+
| 1.25 | 19.95 | +------------------------+------------------------+
1 row in set (0.00 sec)
mysql> SELECT * FROM shop WHERE price = @min_price OR price = @max_price ; +---------+--------+-------+
| article | dealer | price | +---------+--------+-------+
| 0003 | D | 1.25 |
| 0004 | D | 19.95 | +---------+--------+-------+
2 rows in set (0.01 sec)
mysql> 8：使用外键
9：在两个关键字中搜索
可实现的方法有3中：
1：使用AND的情况
2：使用OR的情况
3：使用UNION将两个结果UNION起来
10：计算每天的访问量
（暂时没看懂它是怎么统计的）
建表插入数据
CREATE TABLE t1 (year YEAR(4), month INT(2) UNSIGNED ZEROFILL, day INT(2) UNSIGNED ZEROFILL);
INSERT INTO t1 VALUES(2000,1,1),(2000,1,20),(2000,1,30),(2000,2,2), (2000,2,23),(2000,2,23);SELECT
SELECT year,month,BIT_COUNT(BIT_OR(1\<\<day)) AS days FROM t1 GROUP BY year,month;11：使用AUTO_INCREAMENT
The AUTO_INCREMENT attribute can be used to generate a unique identity for new rows: CREATE TABLE animals ( id MEDIUMINT NOT NULL AUTO_INCREMENT,
name CHAR(30) NOT NULL,
PRIMARY KEY (id)
);
INSERT INTO animals (name) VALUES
('dog'),('cat'),('penguin'),
('lax'),('whale'),('ostrich');
SELECT * FROM animals;
Which returns: +----+---------+
| id | name
| +----+---------+
| 1 | dog
|
| 2 | cat
|
| 3 | penguin |
| 4 | lax
|
| 5 | whale
|
| 6 | ostrich | +----+---------+在Apache中使用MySQL
There are programs that let you authenticate your users from a MySQL database and also let you write
your log files into a MySQL table.
You can change the Apache logging format to be easily readable by MySQL by putting the following
into the Apache configuration file:
LogFormat \
"\"%h\",%{%Y%m%d%H%M%S}t,%>s,\"%b\",\"%{Content-Type}o\", \"%U\",\"%{Referer}i\",\"%{User-Agent}i\""
\
To load a log file in that format into MySQL, you can use a statement something like this:
LOAD DATA INFILE '/local/access_log' INTO TABLE tbl_name
FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"' ESCAPED BY '\\'
The named table shoul