MySQL/5.7
如何下載? Ubuntu下: sudo apt-get install mysql-server
如何連線? mysql -u root -p 輸入密碼
清除資料庫/慎重
DROP DATABASE test;


建立資料庫
CREATE DATABASE test;


顯示已有資料庫
SHOW DATABASES;


選定操作資料庫
USE test;


MySQL資料型別
TINYINT		1位元組			小整數值
INT		4位元組			大整數值
BIGINT		8位元組			極大整數值
FLOAT		4位元組			單精度
DOUBLE		8位元組			雙精度
DATE		YYYY-MM-DD		日期值
TIME		HH:MM:SS		時間值
YEAR		YYYY			年份值
DATETIME	YYYY-MM-DD HH:MM:SS	混合日期和時間值	insert into tweets values('2017-03-02 15:22:22');
TIMESTAMP	YYYYMMDDHHMMSS		時間戳
CHAR		0~255			定長CHAR(20)/20為長度
VARCHAR		0-65535			變長VARCHAR(20)/20為限制長度
TINYBLOB	0~255			小二進位制
TINYTEXT	0~255			小文字
BLOB		0~65535			二進位制
TEXT		0~65535			文字
MEDIUMBLOB	0-16777215		中二進位制
MEDIUMTEXT	0-16777215		中文字
LONGBLOB	0-4294967295		長二進位制
LONGTEXT	0-4294967295		長文字


刪除表/慎重
DROP TABLE students;


表的重新命名（不影響資料）/慎重
RENAME TABLE students TO new_name;


建立表/學生資訊/考試成績/雜貨店
CREATE TABLE students (
	id INT AUTO_INCREMENT PRIMARY KEY,
	first_name CHAR(20),
	last_name CHAR(20),
	email TEXT,
	phone VARCHAR(40),
	birthdate DATE,
	friend_id INT);
CREATE TABLE student_grades (
	student_id INT,
	test TEXT,
	grade INT);
CREATE TABLE groceries (
	id INT AUTO_INCREMENT PRIMARY KEY,
	name TEXT,
	quantity INT);


檢視資料庫所有表
SHOW TABLES;


查看錶結構
DESCRIBE students;
SHOW COLUMNS FROM students;


列的增加（不影響資料）
ALTER TABLE students ADD body TEXT;


列的重新定義（不影響資料）
ALTER TABLE students CHANGE COLUMN body health CHAR(20);


設定或刪除列的預設值
ALTER TABLE students ALTER COLUMN health SET DEFAULT 'OK';
ALTER TABLE students ALTER COLUMN health DROP DEFAULT;


指定刪除某行內容/慎重
DELETE FROM students WHERE id = 3;


加入資訊行/沒有標明的列必須要DEFAULT或者自增
INSERT INTO students (first_name,last_name,email,phone,birthdate,friend_id)
	VALUES ('Peter','Rabbit','
 
[email protected]','555-6666','2002-06-24',2);
INSERT INTO students (first_name,last_name,email,phone,birthdate,friend_id)
	VALUES ('Alice','Wonderland','[email protected]','555-4444','2002-07-04',1);
INSERT INTO students (first_name,last_name,email,phone,birthdate,friend_id)
	VALUES ('Aladdin','Lampland','
 
[email protected]','555-4443','2001-05-10',4);
INSERT INTO students (first_name,last_name,email,phone,birthdate,friend_id)
	VALUES ('Simba','Kingston','[email protected]','555-1111','2001-12-24',3);

INSERT INTO student_grades (student_id,test,grade)
	VALUES (1,'Nutrition',95);
INSERT INTO student_grades (student_id,test,grade)
	VALUES (2,'Nutrition',92);
INSERT INTO student_grades (student_id,test,grade)
	VALUES (1,'Chemistry',85);
INSERT INTO student_grades (student_id,test,grade)
	VALUES (2,'Chemistry',95);

INSERT INTO groceries
	VALUES (1,"Banana",4);
INSERT INTO groceries
	VALUES (2,"Apple",1);
INSERT INTO groceries
	VALUES (3,"Peach",2);


查看錶中所有資訊/檢視組合表資訊
SELECT * FROM students;
SELECT * FROM students,student_grades;


查看錶中指定列的資訊
SELECT first_name,last_name,phone FROM students;


按照某個列排序查看錶中資訊/ASC升序DESC降序
SELECT * FROM groceries ORDER BY quantity ASC;


按照某列排序查看錶中資訊，附帶限定資訊/AND/OR
SELECT * FROM groceries WHERE quantity > 1 AND quantity < 5 ORDER BY quantity DESC;


選定指定字串值的表中資訊/IN也可以NOT IN
SELECT * FROM groceries WHERE name = "Banana" OR name="Apple" OR name="xxx";
SELECT * FROM groceries WHERE name IN ("Banana","Apple","xxx");


選定某列的總和/也可以MIN,MAX/按照分組求和
SELECT SUM(quantity) FROM groceries;
SELECT name,SUM(quantity) FROM groceries GROUP BY name;


巢狀選定
SELECT * FROM students WHERE id IN (SELECT student_id FROM student_grades);


按字串正則表示式選定
SELECT * FROM students WHERE phone LIKE "%444%";


選定時列自定義標題AS,分組統計和
SELECT student_id,SUM(grade) AS total_grades FROM student_grades GROUP BY student_id;


按照id分組統計和，並從結果中選定滿足某個限定結果，GROUP後面才用HAVING
SELECT student_id,SUM(grade) AS total_grades FROM student_grades GROUP BY student_id
	HAVING total_grades > 180;


使用GROUP分組後會自動記錄下該分組的資料行個數，用COUNT(*)即可獲得
SELECT student_id FROM student_grades GROUP BY student_id HAVING COUNT(*) >= 2;


使用CASE來為選定結果添加註釋
SELECT student_id,test,
	CASE
	WHEN grade >= 95 THEN "very good"
	WHEN grade >= 90 THEN "good"
	ELSE "ok"
	END AS "remark"
	FROM student_grades;


不同表中按照某值匹配檢視/後者效率更高並且可以再加個WHERE
SELECT * FROM students,student_grades
	WHERE student_grades.student_id = students.id;
SELECT * FROM students
	JOIN student_grades
	ON student_grades.student_id = students.id
	WHERE grade > 90;


不同表中按照某值匹配檢視，若無匹配也顯示
SELECT * FROM students
	LEFT OUTER JOIN student_grades
	ON student_grades.student_id = students.id;


更新某行中的某列資訊
UPDATE students SET email='
 
[email protected]' WHERE id = 4;


在同一張表中交叉查詢/自我JOIN
SELECT students.first_name,students.last_name,friend.email AS friend_email
	FROM students
	JOIN students friend
	ON students.friend_id = friend.id;


在多個不同表中交叉查詢/要把SELECT id,quantity FROM groceries;中的兩列數字全用對應id學生的姓氏代替
SELECT a.first_name,b.first_name FROM groceries
	JOIN students a
	ON groceries.id = a.id
	JOIN students b
	ON groceries.quantity = b.id;


//**[email protected]**//