在MySQL存储过程的语句中有三个标准的循环方式：WHILE循环，LOOP循环以及REPEAT循环。还有一种非标准的循环方式：GOTO，不过这种循环方式最好别用，很容易引起程序的混乱，在这里就不错具体介绍了。

这几个循环语句的格式如下：
WHILE……DO……END WHILE
REPEAT……UNTIL END REPEAT
LOOP……END LOOP
GOTO。

    下面首先使用第一种循环编写一个例子。
mysql> create procedure pro10()
    -> begin
    -> declare i int;
    -> set i=0;
    -> while i<5 do
    ->     insert into t1(filed) values(i);
    ->     set i=i+1;
    -> end while;
    -> end;//
Query OK, 0 rows affected (0.00 sec)
    在这个例子中，INSERT和SET语句在WHILE和END WHILE之间，当变量i大于等于5的时候就退出循环。使用set i=0；语句是为了防止一个常见的错误，如果没有初始化，i默认变量值为NULL，而NULL和任何值操作的结果都是NULL。
    执行一下这个存储过程并产看一下执行结果：
mysql> delete from t1//
Query OK, 0 rows affected (0.00 sec)
mysql> call pro10()//
Query OK, 1 row affected (0.00 sec)
mysql> select * from t1//
+——-+
| filed |
+——-+
|     0 |
|     1 |
|     2 |
|     3 |
|     4 |
+——-+
5 rows in set (0.00 sec)
    以上就是执行结果，有5行数据插入到数据库中，证明存储过程编写正确无误^_^。

    再来看一下第二个循环控制指令 REPEAT……END REPEAT。使用REPEAT循环控制语句编写下面这个存储过程：
mysql> create procedure pro11()
    -> begin
    -> declare i int default 0;
    -> repeat
    ->     insert into t1(filed) values(i);
    ->     set i=i+1;
    ->     until i>=5
    -> end repeat;
    -> end;//
Query OK, 0 rows affected (0.00 sec)
    这个REPEAT循环的功能和前面WHILE循环一样，区别在于它的执行后检查是否满足循环条件（until i>=5），而WHILE则是执行前检查（while i<5 do）。
    不过要注意until i>=5后面不要加分号，如果加分号，就是提示语法错误。
    编写完成后，调用一下这个存储过程，并查看结果：
mysql> delete from t1//
Query OK, 5 rows affected (0.00 sec)

mysql> call pro11()//
Query OK, 1 row affected (0.00 sec) #虽然在这里显示只有一行数据受到影响，但是下面选择数据的话，还是插入了5行数据。

mysql> select * from t1//
+——-+
| filed |
+——-+
|     0 |
|     1 |
|     2 |
|     3 |
|     4 |
+——-+
5 rows in set (0.00 sec)
一行就是执行结果，实际的作用和使用while编写的存储过程一样，都是插入5行数据。

一、配置文件的修改
    1.#sudo vim /etc/mysql/my.cnf

    找到 bind-address = 127.0.0.1
    注释掉这句话
 
二、Mysql数据库的修改
1) [root@etc etc]# mysql -u  root  -p
Enter password:
2)mysql> use mysql;
3)mysql> select host,user,password from user;
4)grant all privileges on *.* to  root@192.168.15.101  identified by 'password'
 注意： （1）192.168.15.101是欲连接到此Mysql数据库的客户端的IP地址，而不是Mysql数据库所在数据库服务器的IP地址，切记。这里也可以使用'%'代替所有ip
              （2）password就是Mysql数据库root用户的password,根据实际情况需要修改

三、再次用Mysql客户端登陆

本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/bjblues/archive/2008/02/04/2083934.aspx

select id, username from user where id>1
INTERSECT
select id, username from user where id<3

can simply be rewritten to

select id, username from user inner join
(select id, username from user where id <3) as b using (id, username)
where id>1

Java代码

1. CREATE TABLE Movie(   
2. id           INT NOT NULL AUTO_INCREMENT,   
3. name     VARCHAR(60) NOT NULL,   
4. released YEAR NOT NULL,   
5. PRIMARY KEY (id)   
6. ) ENGINE=InnoDB;  

CREATE TABLE Movie(
id           INT NOT NULL AUTO_INCREMENT,
name     VARCHAR(60) NOT NULL,
released YEAR NOT NULL,
PRIMARY KEY (id)
) ENGINE=InnoDB;

Java代码

1. INSERT INTO Movie (name,released) VALUES ('Gladiator',2000);   
2. INSERT INTO Movie (id,name,released) VALUES (NULL,'The Bourne Identity',1998);  

INSERT INTO Movie (name,released) VALUES ('Gladiator',2000);
INSERT INTO Movie (id,name,released) VALUES (NULL,'The Bourne Identity',1998);

Java代码

1. CREATE TABLE Movie(   
2. id          INT NOT NULL,   
3. name     VARCHAR2(60) NOT NULL,   
4. released INT NOT NULL,   
5. PRIMARY KEY (id)   
6. );   
7. CREATE SEQUENCE MovieSeq;  

CREATE TABLE Movie(
id          INT NOT NULL,
name     VARCHAR2(60) NOT NULL,
released INT NOT NULL,
PRIMARY KEY (id)
);
CREATE SEQUENCE MovieSeq;

Java代码

1. INSERT INTO Movie (id,name,released) VALUES (MovieSeq.NEXTVAL,'Gladiator',2000);  

INSERT INTO Movie (id,name,released) VALUES (MovieSeq.NEXTVAL,'Gladiator',2000);

Java代码

1. CREATE OR REPLACE TRIGGER BRI_MOVIE_TRG   
2. BEFORE INSERT ON Movie   
3. FOR EACH ROW   
4. BEGIN   
5.   SELECT MovieSeq.NEXTVAL INTO :new.id FROM DUAL;   
6. END BRI_MOVIE_TRG;   
7. .   
8. RUN;  

CREATE OR REPLACE TRIGGER BRI_MOVIE_TRG
BEFORE INSERT ON Movie
FOR EACH ROW
BEGIN
SELECT MovieSeq.NEXTVAL INTO :new.id FROM DUAL;
END BRI_MOVIE_TRG;
.
RUN;

Java代码

1. INSERT INTO Movie (name,released) VALUES ('The Lion King',1994);  

INSERT INTO Movie (name,released) VALUES ('The Lion King',1994);

NEXTVAL(’sequence’);
CURRVAL(’sequence’);
SETVAL(’sequence’,value);

Java代码

1. DROP TABLE IF EXISTS sequence;   
2. CREATE TABLE sequence (   
3. name              VARCHAR(50) NOT NULL,   
4. current_value INT NOT NULL,   
5. increment       INT NOT NULL DEFAULT 1,   
6. PRIMARY KEY (name)   
7. ) ENGINE=InnoDB;   
8. INSERT INTO sequence VALUES ('MovieSeq',3,5);   
9. DROP FUNCTION IF EXISTS currval;   
10. DELIMITER $   
11. CREATE FUNCTION currval (seq_name VARCHAR(50))   
12. RETURNS INTEGER   
13. CONTAINS SQL   
14. BEGIN   
15.   DECLARE value INTEGER;   
16.   SET value = 0;   
17.   SELECT current_value INTO value   
18.   FROM sequence   
19.   WHERE name = seq_name;   
20.   RETURN value;   
21. END$   
22. DELIMITER ;  

DROP TABLE IF EXISTS sequence;
CREATE TABLE sequence (
name              VARCHAR(50) NOT NULL,
current_value INT NOT NULL,
increment       INT NOT NULL DEFAULT 1,
PRIMARY KEY (name)
) ENGINE=InnoDB;
INSERT INTO sequence VALUES ('MovieSeq',3,5);
DROP FUNCTION IF EXISTS currval;
DELIMITER $
CREATE FUNCTION currval (seq_name VARCHAR(50))
RETURNS INTEGER
CONTAINS SQL
BEGIN
DECLARE value INTEGER;
SET value = 0;
SELECT current_value INTO value
FROM sequence
WHERE name = seq_name;
RETURN value;
END$
DELIMITER ;

Java代码

1. mysql> SELECT currval('MovieSeq');   
2. +---------------------+   
3. | currval('MovieSeq') |   
4. +---------------------+   
5. |                   3 |   
6. +---------------------+   
7. 1 row in set (0.00 sec)   
8. mysql> SELECT currval('x');   
9. +--------------+   
10. | currval('x') |   
11. +--------------+   
12. |            0 |   
13. +--------------+   
14. 1 row in set, 1 warning (0.00 sec)   
15. mysql> show warnings;   
16. +---------+------+------------------+   
17. | Level   | Code | Message          |   
18. +---------+------+------------------+   
19. | Warning | 1329 | No data to FETCH |   
20. +---------+------+------------------+   
21. 1 row in set (0.00 sec)  

mysql> SELECT currval('MovieSeq');
+---------------------+
| currval('MovieSeq') |
+---------------------+
|                   3 |
+---------------------+
1 row in set (0.00 sec)
mysql> SELECT currval('x');
+--------------+
| currval('x') |
+--------------+
|            0 |
+--------------+
1 row in set, 1 warning (0.00 sec)
mysql> show warnings;
+---------+------+------------------+
| Level   | Code | Message          |
+---------+------+------------------+
| Warning | 1329 | No data to FETCH |
+---------+------+------------------+
1 row in set (0.00 sec)

Java代码

1. DROP FUNCTION IF EXISTS nextval;   
2. DELIMITER $   
3. CREATE FUNCTION nextval (seq_name VARCHAR(50))   
4. RETURNS INTEGER   
5. CONTAINS SQL   
6. BEGIN   
7.    UPDATE sequence   
8.    SET          current_value = current_value + increment   
9.    WHERE name = seq_name;   
10.    RETURN currval(seq_name);   
11. END$   
12. DELIMITER ;  

DROP FUNCTION IF EXISTS nextval;
DELIMITER $
CREATE FUNCTION nextval (seq_name VARCHAR(50))
RETURNS INTEGER
CONTAINS SQL
BEGIN
UPDATE sequence
SET          current_value = current_value + increment
WHERE name = seq_name;
RETURN currval(seq_name);
END$
DELIMITER ;

Java代码

1. mysql> select nextval('MovieSeq');   
2. +---------------------+   
3. | nextval('MovieSeq') |   
4. +---------------------+   
5. |                  15 |   
6. +---------------------+   
7. 1 row in set (0.09 sec)   
8.   
9. mysql> select nextval('MovieSeq');   
10. +---------------------+   
11. | nextval('MovieSeq') |   
12. +---------------------+   
13. |                  20 |   
14. +---------------------+   
15. 1 row in set (0.01 sec)   
16.   
17. mysql> select nextval('MovieSeq');   
18. +---------------------+   
19. | nextval('MovieSeq') |   
20. +---------------------+   
21. |                  25 |   
22. +---------------------+   
23. 1 row in set (0.00 sec)  

mysql> select nextval('MovieSeq');
+---------------------+
| nextval('MovieSeq') |
+---------------------+
|                  15 |
+---------------------+
1 row in set (0.09 sec)
mysql> select nextval('MovieSeq');
+---------------------+
| nextval('MovieSeq') |
+---------------------+
|                  20 |
+---------------------+
1 row in set (0.01 sec)
mysql> select nextval('MovieSeq');
+---------------------+
| nextval('MovieSeq') |
+---------------------+
|                  25 |
+---------------------+
1 row in set (0.00 sec)

Java代码

1. DROP FUNCTION IF EXISTS setval;   
2. DELIMITER $   
3. CREATE FUNCTION setval (seq_name VARCHAR(50), value INTEGER)   
4. RETURNS INTEGER   
5. CONTAINS SQL   
6. BEGIN   
7.    UPDATE sequence   
8.    SET          current_value = value   
9.    WHERE name = seq_name;   
10.    RETURN currval(seq_name);   
11. END$   
12. DELIMITER ;  

DROP FUNCTION IF EXISTS setval;
DELIMITER $
CREATE FUNCTION setval (seq_name VARCHAR(50), value INTEGER)
RETURNS INTEGER
CONTAINS SQL
BEGIN
UPDATE sequence
SET          current_value = value
WHERE name = seq_name;
RETURN currval(seq_name);
END$
DELIMITER ;

Java代码

1. mysql> select setval('MovieSeq',150);   
2. +------------------------+   
3. | setval('MovieSeq',150) |   
4. +------------------------+   
5. |                    150 |   
6. +------------------------+   
7. 1 row in set (0.06 sec)   
8.   
9. mysql> select curval('MovieSeq');   
10. +---------------------+   
11. | currval('MovieSeq') |   
12. +---------------------+   
13. |                 150 |   
14. +---------------------+   
15. 1 row in set (0.00 sec)   
16.   
17. mysql> select nextval('MovieSeq');   
18. +---------------------+   
19. | nextval('MovieSeq') |   
20. +---------------------+   
21. |                 155 |   
22. +---------------------+   
23. 1 row in set (0.00 sec)  

package com.founder.demo;

import Java.sql.Connection;
import Java.sql.DriverManager;
import Java.sql.PreparedStatement;
import Java.sql.ResultSet;
import Java.sql.Statement;

public class ImportCSV {

 public static void main(String[] args) {
  try {
   // load the driver into memory
   Class.forName("org.relique.jdbc.csv.CsvDriver");

   // create a connection. The first command line parameter is assumed to
   //  be the directory in which the .csv files are held
   Connection conn = DriverManager
     .getConnection("jdbc:relique:csv:H:\\PythonWorkSpace");

   // create a Statement object to execute the query with
   Statement stmt = conn.createStatement();

   // Select the columns from csv file
   ResultSet results = stmt
     .executeQuery("SELECT ORDER_NO,ARTICLE_NO,CATALOG_NO,DESCRIPTION,QUANTITY,ISO_UNIT,UNIT,MDL_NO,CAS, "
       + " MOLECULA,FORMULA,DENSITY,PRICE_EUR,UN_NO,DANGER_GR,DANGER_CLASS,ZUSATZGEFAHR1,ZUSATZGEFAHR2,R_PHRASES, "
       + " S_PHRASES,DANGER_SYMBOL,STORAGE_TEMPERATURE FROM ABCR");
   
   //MySQL
   Class.forName("com.mysql.jdbc.Driver").newInstance();
   Connection con = Java.sql.DriverManager
     .getConnection(
       "jdbc:mysql://localhost/chemicaldb?useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull",
       "root", "root");

   String sql = "INSERT INTO meryer_abcr (ORDER_NO,ARTICLE_NO,CATALOG_NO,DESCRIPTION,QUANTITY,ISO_UNIT,UNIT,MDL_NO,CAS, "
     + " MOLECULA_FORMULA,MOLECULAR_WEIGHT,DENSITY,PRICE_EUR,UN_NO,DANGER_GROUP,DANGER_CLASS,ZUSATZGEFAHR1,ZUSATZGEFAHR2,R_PHRASES, "
     + " S_PHRASES,DANGER_SYMBOL,STORAGE_TEMPERATURE) values (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)";

   PreparedStatement mstmt = con.prepareStatement(sql);

   // dump out the results and set params
   while (results.next()) {
    mstmt.setString(1, results.getString("ORDER_NO"));
    mstmt.setString(2, results.getString("ARTICLE_NO"));
    mstmt.setString(3, results.getString("CATALOG_NO"));
    mstmt.setString(4, results.getString("DESCRIPTION"));
    mstmt.setString(5, results.getString("QUANTITY"));
    mstmt.setString(6, results.getString("ISO_UNIT"));
    mstmt.setString(7, results.getString("UNIT"));
    mstmt.setString(8, results.getString("MDL_NO"));
    mstmt.setString(9, results.getString("CAS"));
    mstmt.setString(10, results.getString("MOLECULA_FORMULA"));
    mstmt.setString(11, results.getString("MOLECULAR_WEIGHT"));
    mstmt.setString(12, results.getString("DENSITY"));
    mstmt.setString(13, results.getString("PRICE_EUR"));
    mstmt.setString(14, results.getString("UN_NO"));
    mstmt.setString(15, results.getString("DANGER_GROUP"));
    mstmt.setString(16, results.getString("DANGER_CLASS"));
    mstmt.setString(17, results.getString("ZUSATZGEFAHR1"));
    mstmt.setString(18, results.getString("ZUSATZGEFAHR2"));
    mstmt.setString(19, results.getString("R_PHRASES"));
    mstmt.setString(20, results.getString("S_PHRASES"));
    mstmt.setString(21, results.getString("DANGER_SYMBOL"));
    mstmt.setString(22, results.getString("STORAGE_TEMPERATURE"));
    mstmt.execute();
    
    System.out.println(results.getString("ORDER_NO"));
   }
   
   // clean up
   mstmt.close();
   con.close();
   results.close();
   stmt.close();
   conn.close();
  } catch (Exception e) {
   System.out.println("Oops-> " + e);
  }

 }

}

其实很简单，和操作数据库一样，提供了类似数据中的SQL语句来操作CSV文件中的数据。

#encoding=utf-8
from __future__ import with_statement
import MySQLdb
import urllib
from lister import ListerTR

conn = MySQLdb.connect(host="localhost", user="root", passwd="root", db="coocoo", charset="utf8")
cursor = conn.cursor()
cursor.execute("select id, enname from compound where enname != '' and zhname = '' order by id")
row=cursor.fetchall()
for r in row:
    params = urllib.urlencode({'eng2chi':r[1]})      这里组织参数
    sock = urllib.urlopen("http://202.127.145.134/scdb/translate/translate.asp", params)   发送请求，并把参数传过去
    html = sock.read()
    sock.close()
    p = ListerTR()   以下为解析返回的数据代码
    p.feed(html)
    html = p.html
    if u"成功" in html:
        value = p.values[5]
        data = value.strip()
        print r[0], r[1], data    取回翻译成功的内容更新数据库里面的值
        cursor.execute("update compound set zhname = %s where id=%s", (data, r[0]))
        conn.commit()
    else:    把翻译失败的记录给文本文件中
        with open('failture.txt', 'a+') as f:
            f.write(str(r[0])+" | "+str(r[1]))
            f.write('\n')
cursor.close()
conn.close()

      mysql-5.0.19.tar.gz

二. 安装环境:

主服务器:   192.168.0.201

从服务器:   192.168.0.00

三.主服务器配置:

Ø         建立用户
grant replication slave on *.* to user001@192.168.0.200 identified by ‘111111′

Ø         编辑配置文件/etc/my.cnf
server-id = 1
log-bin=mysql-bin
binlog-do-db=test
binlog-ignore-db=mysql

注:

 # grant replication slave on *.* to ‘用户名’@'主机’ identified by ‘密码’;
# binlog-do-db=需要备份的数据库名，可写多行
# binlog-ignore-db=不需要备份的数据库名，可写多行

       # 可在B Slave上做连接测试: mysql -h 192.168.0.200 -u test -p

四.从服务器配置:

Ø        编辑/etc/my.cnf

server-id=2
server-id=2       记得是两个???
log-bin=mysql-bin
master-host=192.168.0.201
master-user=user001
master-password=111111
master-port=3306
replicate-do-db=test
replicate-do-db=test1
# replicate-do-db=test  需要备份的数据库名
# replicate-ignore-db=mysql 忽略的数据库
# master-connect-retry=60 如果从服务器发现主服务器断掉，重新连接的时间差(秒)

先手动同步一下主从服务器中要备份的数据库，再重启主，从服务器。

五.验证是否配置正确:

     # mysql>  slave start;

     # mysql>  show slave status\G;

*************************** 1. row ***************************

             Slave_IO_State: Waiting for master to send event

                Master_Host: 192.168.0.201

                Master_User: repluser1

                Master_Port: 3306

              Connect_Retry: 60

            Master_Log_File: mysql-bin.000045

        Read_Master_Log_Pos: 212

             Relay_Log_File: sky-relay-bin.000054

              Relay_Log_Pos: 235

      Relay_Master_Log_File: mysql-bin.000045

           Slave_IO_Running: Yes

          Slave_SQL_Running: Yes

            Replicate_Do_DB: test,test1

        Replicate_Ignore_DB:

         Replicate_Do_Table:

     Replicate_Ignore_Table:

    Replicate_Wild_Do_Table:

Replicate_Wild_Ignore_Table:

                 Last_Errno: 0

                 Last_Error:

               Skip_Counter: 0

        Exec_Master_Log_Pos: 212

            Relay_Log_Space: 235

            Until_Condition: None

             Until_Log_File:

              Until_Log_Pos: 0

         Master_SSL_Allowed: No

         Master_SSL_CA_File:

         Master_SSL_CA_Path:

            Master_SSL_Cert:

          Master_SSL_Cipher:

             Master_SSL_Key:

      Seconds_Behind_Master: 0

1 row in set (0.00 sec)

确如如下行一致:
Waiting for master to send event
Slave_IO_Running: Yes
Slave_SQL_Running: Yes

其他: ++主服务器上的相关命令
show master status
show slave hosts
show logs
show binlog events
purge logs to ‘log_name’
purge logs before ‘date’
reset master(老版本flush master)
set sql_log_bin=

++从服务器上的相关命令
slave start
slave stop
SLAVE STOP IO_THREAD //此线程把master段的日志写到本地
SLAVE start IO_THREAD
SLAVE STOP SQL_THREAD //此线程把写到本地的日志应用于数据库
SLAVE start SQL_THREAD
reset slave
SET GLOBAL SQL_SLAVE_SKIP_COUNTER
load data from master
show slave status(SUPER,REPLICATION CLIENT)
CHANGE MASTER TO MASTER_HOST=, MASTER_PORT=,MASTER_USER=, MASTER_PASSWORD= //动态改变master信息
PURGE MASTER [before ‘date’] 删除master端已同步过的日志

++产生了mysql-bin.00000x文件可以删除

附一: mysql无法启动:

# /usr/local/mysql//bin/mysqld_safe --user=mysql --log-error=err.txt

# more err.txt 根据里面的提示信息进行判断分析

附二: 解决mysql“Access denied for user 'root'@'localhost'”

mysql -uroot -p
Enter password:
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
修改root用户的密码：
# mysqladmin -uroot -p password 'newpassword' -

文章出处：http://www.diybl.com/course/6_system/linux/Linuxjs/2008622/127458.html

另一种办法是在数据库设计的时候，可能需要大小写敏感，解决方法是建表时候使用BINARY标示。
CREATE TABLE students(
    name VARCHAR(10) BINARY
);

1. 工资5000以上的职员，工资减少10%
2. 工资在2000到4600之间的职员，工资增加15%

--条件1
UPDATE Personnel
SET salary = salary * 0.9
WHERE salary >= 5000;
--条件2
UPDATE Personnel
SET salary = salary * 1.15
WHERE salary >= 2000 AND salary < 4600;

UPDATE Personnel
SET salary = CASE WHEN salary >= 5000
　            THEN salary * 0.9
WHEN salary >= 2000 AND salary < 4600
THEN salary * 1.15
ELSE salary END;

UPDATE SomeTable
SET p_key = CASE WHEN p_key = 'a'
THEN 'b'
WHEN p_key = 'b'
THEN 'a'
ELSE p_key END
WHERE p_key IN ('a', 'b');

--使用IN的时候
SELECT keyCol,
CASE WHEN keyCol IN ( SELECT keyCol FROM tbl_B )
THEN 'Matched'
ELSE 'Unmatched' END Label
FROM tbl_A;
--使用EXISTS的时候
SELECT keyCol,
CASE WHEN EXISTS ( SELECT * FROM tbl_B
WHERE tbl_A.keyCol = tbl_B.keyCol )
THEN 'Matched'
ELSE 'Unmatched' END Label
FROM tbl_A;

1. 只选修一门课程的人，返回那门课程的ID
2. 选修多门课程的人，返回所选的主课程ID

--条件1：只选择了一门课程的学生
SELECT std_id, MAX(class_id) AS main_class
FROM Studentclass
GROUP BY std_id
HAVING COUNT(*) = 1;

STD_ID   MAIN_class
------   ----------
300      4
400      5
500      6

--条件2：选择多门课程的学生
SELECT std_id, class_id AS main_class
FROM Studentclass
WHERE main_class_flg = 'Y' ;

STD_ID  MAIN_class
------  ----------
100     1
200     3

SELECT  std_id,
CASE WHEN COUNT(*) = 1  --只选择一门课程的学生的情况
THEN MAX(class_id)
ELSE MAX(CASE WHEN main_class_flg = 'Y'
THEN class_id
ELSE NULL END
)
END AS main_class
FROM Studentclass
GROUP BY std_id;

STD_ID   MAIN_class
------   ----------
100      1
200      3
300      4
400      5
500      6

CASE col_1
WHEN 1    　   THEN 'Right'
WHEN NULL  THEN 'Wrong'
END

--简单Case函数
CASE sex
WHEN '1' THEN '男'
WHEN '2' THEN '女'
ELSE '其他' END
--Case搜索函数
CASE WHEN sex = '1' THEN '男'
WHEN sex = '2' THEN '女'
ELSE '其他' END

--比如说，下面这段SQL，你永远无法得到“第二类”这个结果
CASE WHEN col_1 IN ( 'a', 'b') THEN '第一类'
WHEN col_1 IN ('a')       THEN '第二类'
ELSE'其他' END

SELECT  SUM(population),
CASE country
WHEN '中国'     THEN '亚洲'
WHEN '印度'     THEN '亚洲'
WHEN '日本'     THEN '亚洲'
WHEN '美国'     THEN '北美洲'
WHEN '加拿大'  THEN '北美洲'
WHEN '墨西哥'  THEN '北美洲'
ELSE '其他' END
FROM    Table_A
GROUP BY CASE country
WHEN '中国'     THEN '亚洲'
WHEN '印度'     THEN '亚洲'
WHEN '日本'     THEN '亚洲'
WHEN '美国'     THEN '北美洲'
WHEN '加拿大'  THEN '北美洲'
WHEN '墨西哥'  THEN '北美洲'
ELSE '其他' END;

SELECT
CASE WHEN salary <= 500 THEN '1'
WHEN salary > 500 AND salary <= 600  THEN '2'
WHEN salary > 600 AND salary <= 800  THEN '3'
WHEN salary > 800 AND salary <= 1000 THEN '4'
ELSE NULL END salary_class,
COUNT(*)
FROM    Table_A
GROUP BY
CASE WHEN salary <= 500 THEN '1'
WHEN salary > 500 AND salary <= 600  THEN '2'
WHEN salary > 600 AND salary <= 800  THEN '3'
WHEN salary > 800 AND salary <= 1000 THEN '4'
ELSE NULL END;

SELECT country,
SUM( CASE WHEN sex = '1' THEN
population ELSE 0 END),  --男性人口
SUM( CASE WHEN sex = '2' THEN
population ELSE 0 END)   --女性人口
FROM  Table_A
GROUP BY country;

CONSTRAINT check_salary CHECK
( CASE WHEN sex = '2'
THEN CASE WHEN salary > 1000
THEN 1 ELSE 0 END
ELSE 1 END = 1 )

CONSTRAINT check_salary CHECK
( sex = '2' AND salary > 1000 )

USE pubs
GO
SELECT
CASE
WHEN price IS NULL THEN 'Unpriced'
WHEN price < 10 THEN 'Bargain'
WHEN price BETWEEN 10 and 20 THEN 'Average'
ELSE 'Gift to impress relatives'
END AS Range,
Title
FROM titles
GROUP BY
CASE
WHEN price IS NULL THEN 'Unpriced'
WHEN price < 10 THEN 'Bargain'
WHEN price BETWEEN 10 and 20 THEN 'Average'
ELSE 'Gift to impress relatives'
END,
Title
ORDER BY
CASE
WHEN price IS NULL THEN 'Unpriced'
WHEN price < 10 THEN 'Bargain'
WHEN price BETWEEN 10 and 20 THEN 'Average'
ELSE 'Gift to impress relatives'
END,
Title
GO

CREATE DATABASE student

2.如何删除数据库

DROP DATABASE student

3.如何备份数据库到磁盘文件

BACKUP DATABASE student to disk=´c:\1234.bak´

4.如何从磁盘文件还原数据库

RESTORE DATABASE studnet FROM DISK = ´c:\1234.bak´

5.怎样创建表？

CREATE TABLE Students (
    ID int IDENTITY ( 1, 1), --自增字段,基数1,步长1
    StudentID char (4) NOT NULL ,
    Name char (10) NOT NULL ,
    Age int NULL ,
    Birthday datetime NULL,
    CONSTRAINT PK_Students PRIMARY KEY (StudentID)  --设置主键
)

CREATE TABLE Subjects (
    ID int IDENTITY ( 1, 1), --自增字段,基数1,步长1
    ClassID char (4) NOT NULL ,
    ClassName char (10) NOT NULL,
    CONSTRAINT PK_Subjects PRIMARY KEY (ClassID)    --设置主键
)

CREATE TABLE Scores (
    ID int IDENTITY ( 1, 1), --自增字段,基数1,步长1
    StudentID char (4) NOT NULL ,
    ClassID char (4) NOT NULL ,
    Score float NOT NULL,
    CONSTRAINT FK_Scores_Students FOREIGN KEY (StudentID) REFERENCES Students(StudentID), --设置外键
    CONSTRAINT FK_Scores_Subjects FOREIGN KEY (ClassID) REFERENCES Subjects(ClassID), --设置外键
    CONSTRAINT PK_Scores PRIMARY KEY (StudentID,ClassID) --设置主键
)

6.怎样删除表？

DROP TABLE Students

7.怎样创建视图？

CREATE VIEW s_s_s
AS
SELECT Students.Name, Subjects.ClassName, Scores.Score
FROM Scores INNER JOIN
      Students ON Scores.StudentID = Students.StudentID INNER JOIN
      Subjects ON Scores.ClassID = Subjects.ClassID

8.怎样删除视图？

DROP VIEW s_s_s

9.如何创建存储过程?

CREATE PROCEDURE GetStudent
@age INT,
@birthday DATETIME
AS
SELECT *
FROM students
WHERE Age = @age AND Birthday = @birthday
GO

10.如何删除存储过程?

DROP PROCEDURE GetStudent

11.如何创建触发器?

CREATE TRIGGER reminder
ON Students
FOR INSERT, UPDATE, DELETE
AS
   EXEC master..xp_sendmail ´MaryM´,
      ´Don´´t forget to print a report for the distributors.´
GO

12.如何删除触发器?

DROP TRIGGER reminder

13.如何创建索引?

CREATE UNIQUE INDEX IX_Students ON Students (Name)

14.如何删除索引?

DROP INDEX Students.IX_Students

15.怎样给表添加字段？

ALTER TABLE Students ADD Address varchar (50) NULL

16.怎样删除表中某个字段？

ALTER TABLE Students DROP COLUMN Address

17.如何设置列的标识属性?

没找到办法

18.如何去掉列的标识属性?

没有找到好的方法,只能是先添加一列,然后把标识列的值更新到新加入的列,删除标识列,再用与标识列相同的名字类型添加一列,用前面加入的列更新该列.如果该标识列是其他表的外键,还要先删除外键约束,很麻烦.谁有好的办法,还请告诉我.

19.如何重设标识列的标识种子?

DBCC CHECKIDENT (Student, RESEED, 1)

20.怎样给表加上主键？

ALTER TABLE Scores ADD CONSTRAINT PK_Scores PRIMARY KEY (StudentID,ClassID)

21.怎样删除表的主键？

ALTER TABLE Scores DROP CONSTRAINT PK_Scores

22.怎样给表添加一个外键？

ALTER TABLE Scores ADD CONSTRAINT FK_Scores_Students FOREIGN KEY (StudentID) REFERENCES Students (StudentID) ON DELETE CASCADE

23.怎样删除表的一个外键？

ALTER TABLE Scores DROP CONSTRAINT FK_Scores_Students

24.怎样给字段加上CHECK约束？

ALTER TABLE Students ADD CONSTRAINT CK_Students CHECK (Age > 0)

25.怎样去掉字段上的CHECK约束？

ALTER TABLE Students DROP CONSTRAINT CK_Students

26.怎样给字段设置默认值？

ALTER TABLE Students ADD CONSTRAINT DF_Students_Age DEFAULT (18) FOR Age

27.怎样移去字段的默认值？

ALTER TABLE Students DROP CONSTRAINT DF_Students_Age

28.修改字段的类型及非空约束

ALTER TABLE Students ALTER COLUMN Age char (10) null
ALTER TABLE Students ALTER COLUMN Age int not null

mysqldump -u root -p --default-character-set=gbk testAcegi > c:\testAcegiDump.sql

mysqldump -u root -p --default-character-set=gbk knightsoft > c:\knightsoft.sql

1.   使用
    import MySQLdb
1.1.   连接
    conn =   MySQLdb.Connection(host, user, password, dbname)
1.2.   选择数据库，如果上面没有指定数据库，则使用此方法指定！
    conn.select_db(’database name’)
1.3.   获得cursor
    cur =   conn.cursor()
1.4.   cursor位置设定
    cur.scroll(int, mode)
    mode可为相对位置或者绝对位置，分别为relative和absolute。
1.5.   select
    cur.execute(‘select clause’)
    例如
    cur.execute(‘select * from mytable’)

    row = cur.fetchall()
    或者：
    row1 = cur.fetchone()
1.6.   insert
    cur.execute(‘inset clause’)
    例如
    cur.execute("insert into user (Name, Password) values ('maggie','12345')")
    conn.commit()

1.7.   update
    cur.execute(‘update  clause’)
    例如
    cur.execute("update user set Name = 'eric chau' where id = 1")
    conn.commit()

1.8.   delete
    cur.execute(‘delete  clause’)
    例如
    cur.execute("delete from user where id = 1")
    conn.commit()


完整代码：

from MySQLdb import Connect

def conn():
    #conn = Connect('localhost','root','root')
    #conn.select_db('eric')
    conn = Connect('localhost','root','root','eric')
    cur = conn.cursor()
    cur.execute('select * from user')
    cur.scroll(0)
    row1 = cur.fetchone()
    print 'id:', row1[0]
    print 'name:', row1[1]
    print 'password:', row1[2]
    #cur.execute("insert into user (Name, Password) values ('maggie','12345')")
    #cur.execute("update user set Name = 'eric chau' where id = 1")
    cur.execute("delete from user where id = 11")
    conn.commit()
if __name__=='__main__':
    conn()