鏈接本地?cái)?shù)據(jù)庫(kù)，下載xampp以及Navicat

查詢表中某個(gè)字段

SELECT name FROM ylan_student?

查詢表中多個(gè)字段

SELECT name,age FROM ylan_student

關(guān)鍵詞 DISTINCT 用于返回唯一不同的值

SELECT DISTINCT age FROM ylan_student

選取年齡大于23的人的姓名

SELECT name FROM ylan_student WHERE age > 23

年齡為23且為女性的人的信息

SELECT * FROM ylan_student WHERE age=23 AND sex='女'

SELECT * FROM ylan_student WHERE age=23 OR sex='女'

SELECT * FROM ylan_student WHERE(age=23 OR age=21)AND sex='男'

年齡排序

SELECT * FROM ylan_student ORDER BY age

插入一條數(shù)據(jù)(全部字段)

INSERT INTO ylan_student VALUES('李喜光',24,'男',1,1)

更新數(shù)據(jù)

UPDATE ylan_student SET name = 'arc' WHERE name = '李喜光'AND age=24

刪除數(shù)據(jù)

DELETE FROM ylan_student WHERE name = 'adc'?

刪除所有行

DELETE FROM ylan_student

創(chuàng)建表?

CREATE TABLE Persons

(

//自動(dòng)增加

Id_P int NOT NULL AUTO_INCREMENT,

LastName varchar(255),

FirstName varchar(255),

Address varchar(255),

City varchar(255),

//主鍵

PRIMARY KEY(id_P)

)

修改表名

rename table Persons to ylan_student2

取三條數(shù)據(jù)

SELECT *

FROM ylan_student

LIMIT 3

COUNT(*) 函數(shù)返回表中的記錄數(shù)：

SELECT COUNT(*)FROM table_name;

平均成績(jī)降序排列以及學(xué)生的信息

SELECT? (score.mathe + score.chainese + score.english)/3? as avgs,student.*?

FROM student,score?

WHERE student.id=score.student_id ORDER BY avgs DESC;