MariaDB數據庫命令與SQL語句
mysql
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sql
-h,--host= 服務器主機,默認爲localhostide
-p,--passowrd= 用戶密碼,建議使用-p,默認爲空密碼函數
ip socket:監聽在tcp的3306端口,支持遠程通訊
(1)mysql -uUSER -pPASSWORD,鏈接數據庫,此處也能夠輸入mysql -uUSER -p,回車後彈出輸入密碼也能夠。指令中-u後的用戶和-p後的密碼與各自的選項沒有空格
(2)mysql -uroot -pPASSWORD < /路徑/DBFILE,導入數據庫
mysql_secure_installation 一個腳本,輔助及設置工具
mysqladmin 基於mysql協議管理mysql的工具
五、若是寫腳本須要插入SQL數據,能夠將命令按照SQL語句寫入一個文件,此時用命令
mysql -uUSER -pPASSWORD < SQLFILE
注:/etc/my.cnf的[mysqld]下添加skip_networking=1,表示關閉遠程端口,只能本機鏈接本機數據庫
$MYSQL_HOME/my.cnf Server-specific 選項
注:工做中可能須要更改數據庫提示符以區分環境,建議在/etc/profile.d/下新建個.sh文件,裏面寫上export MYSQL_PS1="(\u@\h \v)[\d]>",以後 . 啓動一次該腳本
或者在/etc/my.cnf.d/mysql-clients.cnf的[mysql]下添加
2、服務器端命令
(1)數據庫對象:數據庫、表、索引、視圖、用戶、存儲過程、函數、觸發器、事件調度器等
(1)DDL: Data DefinationLanguage 數據定義語言
(2)DML: Data Manipulation Language數據操縱語言
(3)DCL:Data Control Language 數據控制語言
(4)DQL:Data Query Language 數據查詢語言
drop database name 直接刪除數據庫,不提醒
show table status from DBNAME\G 查看某個數據庫的存儲引擎
show create DBNAME/TBLNAME\G 查看數據庫或者表的存儲引擎
注:像對於數據庫增刪改操做都是須要慎重的操做,所以鏈接數據庫時,最好須要mysql -U鏈接,或者/etc/my.cnf.d/my-clients.cnf文件中[mysqld]下添加safe_upgrade,這樣系統對危險操做會提示或者拒絕
(1)CREATE TABLE students (id int UNSIGNED NOT NULL PRIMARY KEY,name VARCHAR(20)NOT NULL,age tinyint UNSIGNED);
創建students表,字段有id(id爲正整數,無符號,不能爲空而且設置爲主鍵)、姓名(可變字段長度爲20,不能爲空)、年齡(小整數型,無符號)
(2)CREATE TABLE students2 (id int UNSIGNED NOT NULL ,name VARCHAR(20) NOT NULL,age tinyint UNSIGNED,PRIMARY KEY(id,name));
創建students2表,字段有id(id爲正整數,無符號,不能爲空)、姓名(可變字段長度爲20,不能爲空)、年齡(小整數型,無符號),主鍵設置爲複合主鍵(id,name)
(3)ALTER TABLE students RENAME s1;
(4)ALTER TABLE s1 ADD phone varchar(11) AFTER name;
修改表格s1,在name字段後添加phone字段,該字段爲可變長度字符型,11個字節
注意:alter沒有before字段,若是插入的字段在首列,用FIRST
(5)ALTER TABLE s1 MODIFY phone int;
(6)ALTER TABLE s1 CHANGE COLUMN phone mobile char(11);
修改表格s1,更改字段phone爲mobile,該字段爲固定長度字符型,11個字節長度上限
(7)ALTER TABLE s1 DROP COLUMN mobile;
(9)ALTER TABLE students ADD gender ENUM('m','f')
修改表格students,添加字段gender,取值只有m、f
(10)ALETR TABLE students CHANGE id sid int UNSIGNED NOT NULL PRIMARY KEY;
修改表格students,改變字段id爲sid,定義sid無符號,不爲空且爲主鍵
(11)ALTER TABLE students ADD UNIQUE KEY(name);
(12)ALTER TABLE students ADD INDEX(age);
(14)SHOW INDEXES FROM students;
(15)ALTER TABLE students DROP age;
(16)INSERT INTO students VALUES(1,'tom','m'),(2,'alice','f');
(知道表結構只有id姓名性別這三個字段狀況下)插入學生表信息
(17)INSERT INTO students(id,name) VALUES(3,'jack'),(4,'allen');
(18)SELECT * FROM students WHERE id < 3;
(19)SELECT * FROM students WHERE gender='m';
(20)SELECT * FROM students WHERE gender IS NULL;
(21)SELECT * FROM students ORDER BY name DESC LIMIT 1,2;
按name倒序排列,跳過第一個,查詢學生表跳事後的前兩條信息
(22)SELECT * FROM students WHERE id >=2 and id <=4
(23)SELECT * FROM students WHERE id in ('2','4')
(24)SELECT * FROM students WHERE id BETWEEN 2 AND 4
(25)SELECT * FROM students WHERE name LIKE ‘t%’
(26)SELECT * FROM students WHERE name RLIKE '.*[lo].*';
(27)SELECT id stuid,name as stuname FROM students
查詢字段id、stuid、name(顯示結果以stuname)
注意:使用group by分組語句時,查詢的數據內容一般會將group by後的字段也一併加入select語句以後做爲查詢結果的區分,而且查詢語句中若是有判斷條件語句,分組前對結果的條件判斷依舊用where,分組後對結果的條件判斷用having,舉例
select ClassID,avg(Age),name from students where gender='f' group by ClassID having name like 'L%';
從學生表中查詢ClassID,avg(Age)、name字段,條件爲gender值爲f的記錄,並以ClassID爲單位進行分組,分組後的結果篩選出name記錄裏以L開頭的記錄
FROM tb1 LEFT JOIN tb2 ON tb1.col=tb2.col
FROM tb1 RIGHT JOIN tb2 ON tb1.col=tb2.col
視圖:view,虛表,保存有實表的查詢結果,若是咱們常常用到一句很長的SQL語句,爲避免每次都輸入那麼長的語句,此時能夠創建視圖:create view VIEWNAME as SQLSENTENCE;等待下次引用就能夠select * from VIEWNAME;直接查詢。舉例說明create view view_students_score as select s.stuid as stu_id,s.name as stu_name,sc.score,c.course from students as s inner join scores sc on s.stuid=sc.stuid inner join courses c on sc.courseid=c.courseid;該語句建立學生成績表視圖,等下次再用該表時候用命令select * from view_students_score;便可