mysql

一、MySQL的SQL语句

First column	Second column
SQL	Structure Query Language
DDL(Data Definition Language )	create , drop , alter
DML(Data Manipulation Language )	insert , update , delete
manipulation	[me nipu'leition] 操纵
update	修改

二、Creating and Using a Database

Suppose that you have serveral pets in your home (your menagerie) and you would like to keep track of various types of information about them.You can do so by creating tables to hold your data and loading them with the desired information.

• Creating a database

• Create a table

• Load data into table

• Retrieve data from the table in various ways

• use multiple tables

word	translation
menagerie	[me'naigeri]小动物园
UTF-8	8-bit Unicode Transformation Format,万国码
format	版式
transformation	变换
snoop	窥探，探听

三、Creating and Selecting a Database

• If the administrator creates your database for you when setting up your permissions,you can begin using it.Otherwise,you need to create it yourself:

mysql>CREATE DATABASE menagerie;

• Creating a database does not select it for use;you must do that explicitly.To make menagerie the current database,use this statement:

mysql>USE menagerie
Database changed

四、Creating a Table

The harder part is deciding what the structure of your database should be:what tables you need and what columns should be in each of them.

You want a table that contains a record for each of your pets.This can be the pet table,and it should contain,as a bare minimum,each animal's name.Because the name by itself is not very interesting,the table should contains other information.For example,if more than one person in your family keeps pets,you might want to list each animal's owner.You might also want to record some basic descriptive information such as species and sex.

How about age?That might be of interesting,but it is not a good thing to store in a database.Age changes as time passes,which means you'd have to update your records often.Instead,it is better to store a fixed value such as data of birth.Then,whenever you need age,you can calculate it as the difference between the current data and the birth data.MySQL provides functions for doing date arithmetic,so this is not difficult.Storing birth data rather than age has other advantages,too:

• You can use the databases for tasks such as generating reminder for upcoming pet birthdays.(If you think this type of query is somewhat silly,note that it is the same question you might ask in the context of a business database to identify clients to whom you need to send out birthday greetings in the current week or month,for that computer-assisted personal touch.)

• You can calculate age in relation to dates other than the current date.For example,if you store death date in the database,you can easily calculate how old a pet was when it died.

You can probably think of other types of information that would be useful in the pet table,but the ones identified so far are sufficient:name,owner,species,sex,birth,and death.

Use a CREATE TABLE statement to specify the layout of your table:

mysql>CREATE TABLE pet (name VARCHAR(20),owner VARCHAR(20),species VARCHAR(20),sex CHAR(1),birth DATA,death DATA);

word	translation
descriptive	描写的，描述的，分类的
bare minimum	最低限度
generating	生成
somewhat	稍微，有点
sufficient	充足的，足够的
specify	指定，详述
specify the layout	指定布局
species	物种

四、Loading Data into a Table

After creating your table,you need to populate it.The LOAD DATA and INSERT statements are useful for this.

Suppose that your pet records can be described as shown here.(Observe that MySQL expects dates in 'YYYY-MM-DD'format;this may be different from what you are used to)

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	1979-08-31	1995-07-29
Chirpy	Gwen	bird	f	1998-09-11	NULL
Whislter	Gwen	bird	NULL	1997-12-09	NULL
Slim	Benny	Snake	m	1996-04-29	NULL
Puffball	Diane	hamster	f	1999-03-30

五、Deleting Data from a Table

delete from pet where name='Whistler'

六、Loading Data into a Table

mysql>LOAD DATA LOCAL INFILE'/path/pet.txt'INTO TABLE pet
     >LINES TERMINATED BY '
';

七、pet.txt

Buffy	Harold	dog	        f	1989-05-13	NULL
Fang	Benny	dog	        m	1990-08-27	NULL
Bowser	Diane	dog	        m	1979-08-31	NULL
Chirpy	Gwen	bird	    f	1998-09-11	NULL
WhistlerGwen	bird	  NULL	1997-12-09	NULL
Slim	Benny	Snake		m	1996-04-29	NULL
PuffballDiane	hamster		f	1999-03-30	NULL

八、MySQL的SQL语句

First column	Second column
SQL	Structure Query Language
DDL(Data Definition Language )	create , drop , alter
DML(Data Manipulation Language )	insert , update , delete
manipulation	[me nipu'leition] 操纵
update	修改

九、Loading Data into a Table

You could create a text file pet.txt containing one record per line,with values separated by tabs,and given in the order in which the columns were listed in the CREATE TABLE statement.For missing values (shch as unknown sexes or death dates for animals that are still living),you can use NULL valuesl.To represent these in your text file,use N(blackflash,capital-N).For example,the record for Whistler the bird would look like this(where the whitespace between values is a single tab character):

Whistler	Gwen	bird	N	1997-12-09	N

If you created the file on Windows with an editor that uses as a line terminator,you should use this statement instead:

mysql>LOAD DATA LOCAL INFILE'/path/pet.txt'INTO TABLE pet
     >LINES TERMINATED BY '
';

十、Retrieving Informatica from a Table

The SELECT statement is used to pull information from a table.The general form the statement is:

SELECT what_to_select
FROM which_table
WHERE conditions_to_satisfy;

• what_to_select indicates what you want to see.This can be a list of columns

• • indicate "all columns"

-which_table indicates the tables from which you want to retrieve data.The WHERE clause is optional.

• conditions_to_satisfy specifies one or more conditions that rows must satisfy to quality for retrieval.

word	translation
retrieval	检索
specify	指定；详述
terminated	结束

十一、DELETING A TABLE

delete from table where 1=1;

after that,we can use the statement :

DESCRIBE pet;

十二、Loading data into a table

mysql>LOAD DATA LOCAL INFILE 'E:pet.txt' INTO TABLE pet
     >LINES TERMINATED BY '
';