鏈接本地數(shù)據(jù)庫，下載xampp以及Navicat
查詢表中某個字段
SELECT name FROM ylan_student?
查詢表中多個字段
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;
