常用sql語句（mysql測試）

DB數據庫，Database
DBMS數據庫管理系統，DatabaMemanagmentSystem
SQL結構化查詢語言，structure Query Language

開啟服務
net start mysql80

登錄
mysql -u root -p

顯示數據庫

show databases;

使用數據庫
use mysql;

顯示數據庫表
show tables;
show tables from mysql;

顯示數據庫
select database();

desc stuinfo;

創建數據庫
create database test;

創建數據庫表

create table customer(id int,name varchar(20),password varchar(20),email varchar(30));

刪除某列

alter table customer drop id;

插入一條數據
insert into stuinfo(id,name) values(1,'John');

查詢
select * from stuinfo;

按時間查詢：

select * from test where date_format(createtime,'%Y-%m-%d') between '2020-01-01' and '2021-01-01';

select * from test where createtime between '2020-01-01 00:01:01' and '2021-01-01 01:01:01';

select * from test where createtime between '2020-01-01 00:01:01' and '2021-01-01 01:01:01';

修改
update stuinfo set name='jack' where id=1;

刪除字段

 alter table songinfo drop id;

刪除值
delete from stuinfo where id=1;

刪除某個表的所有數據

 delete from videos;

或

truncate table videos;

插入新字段在...之后（增加字段）

alter table songinfo add id int primary key auto_increment after score;

插入新字段最前面

alter table songinfo add id int primary key auto_increment first;

插入布爾型

alter table post add essence bit;

重命名數據庫表

rename table oldname to newname;

重置id

alter table news auto_increment=1;

 修改字段名

alter table groupcategory change title grouptitle varchar(10);

修改字段類型

alter table t_hp_new modify column thumb blob;

升序/倒序查詢

select * from user order by id asc;

select * from user order by id desc;

顯示版本
select version();

修改密碼

ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'password';

或者

SET PASSWORD FOR 'root'@'localhost' = PASSWORD('123456');

復制數據庫表到另一個表

create table gg_admin_upload select * from guessgame.gg_admin_upload;

 忘記密碼

打開my.cnf

在[mysqld]里加入，skip-grant-tables

重啟mysql,在輸入密碼的時候直接回車免密碼登錄；

運行 use mysql

update user set authentication_string=password('yourPassword') where user='root'

一些舊的數據庫版本可能是：UPDATE user SET Password = password ( 'yourPassword' ) WHERE User = 'root' ;

在刪除my.conf里面的skip-grant-tables

導出數據庫

mysqldump -uroot -p密碼 database_name>d:/database_name.sql

導入數據庫

create database database_name

use database database_name

source /home/database_name.sql

保存圖片為二進制數據流

 創建表：create table pic_bin(id INT PRIMARY KEY AUTO_INCREMENT,filename VARCHAR(100),data MEDIUMBLOB);

java存儲代碼

try {
                conn = JdbcUtil.connection();
                String sql1="insert into pic_bin(filename,data) values(?,?)";
                ps = conn.prepareStatement(sql1);
                ps.setObject(1,"a.jpg");

                InputStream in=new FileInputStream("C:\\Users\\Administrator\\Desktop\\test.jpg");
                ps.setObject(2,in);

                ps.execute();
            }catch (Exception e){
                e.printStackTrace();
            }finally {

java讀取代碼

try {
                conn = JdbcUtil.connection();
                String sql1="select filename,data from pic_bin where id=?";
                ps = conn.prepareStatement(sql1);
                ps.setObject(1,"1");

                rs=ps.executeQuery();

                if(rs.next()){
                    String filename=rs.getString("filename");


                    InputStream in=rs.getBinaryStream("data");

                    OutputStream out=new FileOutputStream("f:\\"+filename);
                    out.write(in.readAllBytes());

                    out.close();
                }

 一些配置

Incorrect integer value: '' for column 'loginIP' at row 1

修改my.ini

;sql-mode="STRICT_ALL_TABLES,ERROR_FOR_DIVISION_BY_ZERO,NO_ZERO_DATE,NO_ZERO_IN_DATE,NO_AUTO_CREATE_USER"
sql-mode="NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION"

重啟即可

設置浮點數

update table_name set column=floor(1 + rand()*9);