1 連接MYSQL服務器：mysql–uroot –p123456

查看中文問題

show variables like 'character%';

2 修改mysql的字符集，退出mysql提示符界面：

mysql -uroot -p--default_character_set=gbk;

3? 數據庫的操作：創建，查看，修改，刪除

???????? *創建：

?????????????????? 創建一個名稱為mydb1的數據庫。

??????????????????????????? createdatabase mydb1;

?????????????????? 創建一個使用utf-8字符集的mydb2數據庫。

???????? ?????????????????? create database mydb2character set utf8;

?????????????????? 創建一個使用utf-8字符集，并帶校對規則的mydb3數據庫。

??????????????????????????? createdatabase mydb3 character set utf8 collate utf8_general_ci;

???????? *查看:

?????????????????? 顯示所有數據庫

??????????????????????????? showdatabases;

?????????????????? 顯示創建數據庫的語句信息

??????????????????????????? showcreate database mydb2;

???????? *修改:

?????????????????? 修改mydb1的字符集為gbk(不能修改數據庫名)

??????????????????????????? alterdatabase mydb1 character set utf8;?????

???????? *刪除:

?????????????????? 刪除數據庫mydb2

??????????????????????????? dropdatabase mydb1;

?

4 表的操作：創建，查看，修改，刪除

??? usemydb2;

???????? *創建：

?????????????????? 根據實體類Person創建表person

??????????????????????????? Person{

???????????????????????????????????? intid;

???????????????????????????????????? Stringname;

??????????????????????????? }

??????????????????????????? createtable person(

???????????????????????????????????? idint,

???????????????????????????????????? namevarchar(20)

??????????????????????????? );

?????????????????? mysql中的數據類型：

??????????????????????????? bit1位　但可以指定位數，如：bit<3>

??????????????????????????? int2字節 可以指定最大位數，如：int<4>　最大為4位的整數

??????????????????????????? float2個字節　可以指定最大的位數和最大的小數位數，如：float<5,2> 最大為一個5位的數，小數位最多2位

??????????????????????????? double　4個字節　可以指定最大的位數和最大的小數位數，如：float<6,4> 最大為一個6位的數，小數位最多4位

??????????????????????????? char　必須指定字符數,如char(5) 為不可變字符　即使存儲的內容為'ab',也是用5個字符的空間存儲這個數據

??????????????????????????? varchar　必須指定字符數,如varchar(5) 為可變字符　如果存儲的內容為'ab',占用2個字符的空間；如果為'abc',則占用3個字符的空間

??????????????????????????? text:大文本(大字符串)

??????????????????????????? blob：二進制大數據　如圖片，音頻文件，視頻文件

??????????????????????????? date:日期　如：'1921-01-02'

??????????????????????????? datetime:日期時間　如：'1921-01-02 12:23:43'

??????????????????????????? timeStamp:時間戳，自動賦值為當前日期時間

???????????????????????????

???????? ???????? 創建一個員工表

??????????????????????????? createtable employee(id int,name varchar(20),sex bit,birthday date,salarydouble,entry_date date,resume text);

???????? *查看：

?????????????????? 查看所有的表：

??????????????????????????? showtables;

?????????????????? 查看指定表的創建語句

??????????????????????????? showcreate table employee;

??????????????????????????? mysql表 名稱區分大小寫

?????????????????? 顯示指定表的結構：

??????????????????????????? descemployee;

???????? *刪除：

?????????????????? 刪除employee表

?????????????????? droptable employee;

???????? *修改表：

???????create table worker(id int,name varchar(20),sex bit,birthday date,salarydouble,entry_date date,resume text);

?????????????????? 增加一個字段：altertable worker add column height double;

?????????????????? 修改一個字段：altertable worker modify column height float;

?????????????????? 刪除一個字段：altertable worker drop column height;

?????????????????? 更改表名：renametable employee to worker;

?????????????????? 修改表的字符集:altertable worker character set gbk;

????????

5 表數據的CRUD

???????? *C(create增加數據) Insert語句

?????????????????? 新建Employee表并表中添加一些記錄

??????????????????????????? createtable employee(

???????????????????????????????????? idint,

???????????????????????????????????? namevarchar(20),

???????????????????????????????????? sexbit,

???????????????????????????????????? birthdaydate,

???????????????????????????????????? salarydouble,

???????????????????????????????????? entry_datedate,

???????????????????????????????????? resumetext

??????????????????????????? );

???????????????????????????

??????????????????????????? insertinto employee(id,name,sex,birthday,salary,entry_date,resume) values(1,'張三',1,'1983-09-21',15000,'2012-06-24','一個大牛');

??????????????????????????? insertinto employee(id,name,sex,birthday,salary,entry_date,resume) values(2,'李四',1,'1984-09-21',10000,'2012-07-24','一個中牛');

??????????????????????????? insertinto employee(id,name,sex,birthday,salary,entry_date,resume) values(3,'王五',0,'1985-09-21',7000,'2012-08-24','一個小牛');

??????????????????????????? deletefrom employee where id=1

?

??????????????????????????? createtable employee(?? id int,namevarchar(20),sex bit,birthday date,salary double,entry_date date,resume text);

????????

???????? *U(update更新數據) Update語句

?????????????????? 將所有員工薪水都增加500元。

??????????????????????????? updateemployee set salary=salary+500;

?????????????????? 將王五的員工薪水修改為10000元，resume改為也是一個中牛

??????????????????????????? updateemployee set salary=10000,resume='也是一個中牛' where name='王五';

???????? *D(drop刪除數據) Delete語句

?????????????????? 刪除表中姓名為王五的記錄。

??????????????????????????? deletefrom employee where name='王五';

?????????????????? 刪除表中所有記錄。

??????????????????????????? deletefrom employee; --可以有條件，但刪除所有記錄差了一點

?????????????????? 使用truncate刪除表中記錄。

??????????????????????????? truncateemployee;--無條件效率高

????????

???????? 6? *R(Retrieve查找數據) Select語句?

?????????????????? 準備環境：

??????????????????????????? createtable student(

??????????????????????????? idint,

??????????????????????????? namevarchar(20),

??????????????????????????? chineseint,

??????????????????????????? englishint,

??????????????????????????? mathint

??????????????????????????? );

?

??????????????????????????? insertinto student(id,name,chinese,english,math) values(1,'何東',80,85,90);

??????????????????????????? insertinto student(id,name,chinese,english,math) values(2,'權箏',90,95,95);

??????????????????????????? insertinto student(id,name,chinese,english,math) values(3,'何南',80,96,96);

??????????????????????????? insertinto student(id,name,chinese,english,math) values(4,'葉坦',81,97,85);

??????????????????????????? insertinto student(id,name,chinese,english,math) values(5,'何西',85,84,90);

??????????????????????????? insertinto student(id,name,chinese,english,math) values(6,'丁香',92,85,87);

??????????????????????????? insertinto student(id,name,chinese,english,math) values(7,'何北',75,81,80);

??????????????????????????? insertinto student(id,name,chinese,english,math) values(8,'唐嬌',77,80,79);

??????????????????????????? insertinto student(id,name,chinese,english,math) values(9,'任知了',95,85,85);

??????????????????????????? insertinto student(id,name,chinese,english,math) values(10,'王越',94,85,84);

?

?????????????????? 查詢表中所有學生的信息。

??????????????????????????? select* from student;

?????????????????? 查詢表中所有學生的姓名和對應的英語成績。

??????????????????????????? selectname,english from student;

?????????????????? 過濾表中重復數據。

??????????????????????????? selectenglish from student;

??????????????????????????? selectDISTINCT english from student;

??????????????????????????? selectDISTINCT english,name from student;

?

??????????????????????????? selectenglish+chinese+math from student;

??????????????????????????? selectenglish+chinese+math as 總分 from student;

???????? ?????????????????? selectname,english+chinese+math as 總分 from student;

?

?????????????????? 在所有學生英語分數上加10分特長分。

??????????????????????????? selectname,english+10 from student;

?????????????????? 統計每個學生的總分。

??????????????????????????? selectenglish+chinese+math from student;

?????????????????? 使用別名表示學生分數

??????????????????????????? selectname,english+chinese+math as 總分 from student;

??????????????????????????? selectname,english+chinese+math 總分 from student;

?

?????????????????? 查詢姓名為何東的學生成績

??????????????????????????? select* from student where name='何東';

?????????????????? 查詢英語成績大于90分的同學

??????????????????????????? select* from student where english>90;

?????????????????? 查詢總分大于250分的所有同學

??????????????????????????? select* from student where english+chinese+math>250;

?

?????????????????? 查詢英語分數在 85－95之間的同學。

??????????????????????????? select* from student where english>=85 and english<=95;

??????????????????????????? select* from student where english between 85 and 95;

?????????????????? 查詢數學分數為84,90,91的同學。

??????????????????????????? select* from student where math=84 or math=90 or math=91;

??????????????????????????? select* from student where math in(84,90,91);

???????? ???????? 查詢所有姓何的學生成績。

??????????????????????????? select* from student where name like '何%';

?????????????????? 查詢數學分>85，語文分>90的同學。

??????????????????????????? select* from student where math>85 and chinese>90;

?

?????????????????? 對數學成績排序后輸出。

??????????????????????????? select* from student order by math;

?????????????????? 對總分排序后輸出，然后再按從高到低的順序輸出

??????????????????????????? select* from student order by math+chinese+english desc;

?????????????????? 對姓何的學生成績排序輸出

??????????????????????????? select* from student where name like '何%' order by math+chinese+english desc;

??????????????????????????? selectname, math+chinese+english from student where name like '何%' order bymath+chinese+english desc;

?

?????????????????? 統計一個班級共有多少學生？

??????????????????????????? selectcount(*) from student;

?????????????????? 統計數學成績大于90的學生有多少個？

??????????????????????????? selectcount(*) from student where math>90;

?????????????????? 統計總分大于250的人數有多少？

??????????????????????????? selectcount(*) from student where math+chinese+english>250;

?

?????????????????? 統計一個班級數學總成績？

??????????????????????????? selectsum(math) from student;

?????????????????? 統計一個班級語文、英語、數學各科的總成績

??????????????????????????? selectsum(math), sum(chinese), sum(english) from student;

?????????????????? 統計一個班級語文、英語、數學的成績總和

??????????????????????????? selectsum(math+chinese+english)from student;

??????????????????????????? selectsum(math)+sum(chinese)+sum(english) from student;

?

?????????????????? 求一個班級數學平均分？

??????????????????????????? selectavg(math) from student;

?????????????????? 求一個班級總分平均分

??????????????????????????? selectavg(math+chinese+english)from student;

??????????????????????????? selectavg(math)+avg(chinese)+avg(english) from student;

?

?????????????????? 求班級最高分和最低分

??????????????????????????? selectmax(math+chinese+english),min(math+chinese+english) from student;

????????

7 綜合性練習：為學生表，增加一個班級列，然后訓練分組查詢

?????????????????? 查出各個班的總分，最高分

??????????????????????????? 準備環境

???????????????????????????????????? 給表添加一個字段：altertable student add column class_id int;

???????????????????????????????????? 更新表：

?????????????????????????????????????????????? updatestudent set class_id=1 where id<=5;

?????????????????????????????????????????????? updatestudent set class_id=2 where id>5;

??????????????????????????? selectsum(math+chinese+english),max(math+chinese+english) from student group byclass_id;

?

?????????????????? 查詢出班級總分大于1300分的班級ID

??????????????????????????? selectclass_id from student group by class_id havingsum(math+chinese+english)>1300;

??????????????????????????? selectclass_id from student where sum(math+chinese+english)>1300 group by class_id;

?????????????????? note:where和group區別: 在wehre子句中不能使用分組函數

??????????????????

??????????????????

?

8? 時間和日期

?????????????????? mysql>select year (now()), month(now()), day(now()) , date(now());

?????????????????? +--------------+--------------+------------+-------------+

?????????????????? |year (now()) | month(now()) | day(now()) | date(now()) |

?????????????????? +--------------+--------------+------------+-------------+

?????????????????? |?? ??????2014 |??????????? 9 |????????? 7 | 2014-09-07? |

?????????????????? +--------------+--------------+------------+-------------+

????????

?????????????????? selectdate_add(now(), INTERVAL 2 year) from dual;／／增加兩年

?????????????????? selectcharset('name')? employee;

?????????????????? selectdate_add(now(), INTERVAL -1 day) 昨天, now() 今天, date_add(now(), INTERVAL +1 day) 明天;

?

9 字符串相關函數

???????? selectconcat( charset('name'), 'aaaa') 自定義 from dual;

?

?

10 表的約束　　

???????? *定義主鍵約束　primarykey:不允許為空，不允許重復

???????? *定義主鍵自動增長　auto_increment

???????? *定義唯一約束　unique

???????? *定義非空約束　notnull

???????? *定義外鍵約束　constraintordersid_FK foreign key(ordersid) references orders(id)

???????? *刪除主鍵：altertable tablename drop primary key ;

?

???????? createtable myclass

???????? (

?????????????????? idINT(11) primary key auto_increment,

?????????????????? namevarchar(20) unique

???????? );

????????

???????? createtable student(

?????????????????? idINT(11) primary key auto_increment,

?????????????????? namevarchar(20) unique,

?????????????????? passwdvarchar(15) not null,

?????????????????? classidINT(11),? #注意這個地方不要少逗號

?????????????????? constraintstu_classid_FK? foreign key(classid)references myclass(id)

???????? );

????????

?

總結

以上是生活随笔為你收集整理的3.mysql的中文问题，database级操作，表级操作，数据CRUD,分组操作，时间和日期，字符串相关函数，表的约束的全部內容，希望文章能夠幫你解決所遇到的問題。

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