[8월 18일] SQL

 

[root@localhost ~]# systemctl start mariadb
[root@localhost ~]# mysql_secure_installation

 

@mariadb 접속

[root@localhost ~]# mysql -u root -p

Enter password: Welcome to the MariaDB monitor. Commands end with ; or \g. Your MariaDB connection id is 13 Server version: 10.5.27-MariaDB MariaDB Server Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. MariaDB [(none)]>

 

pharsing : 번역

 

@ in mariadb

MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql | | performance_schema |
+--------------------+
3 rows in set (0.000 sec)

@ create,drop 연습
MariaDB [(none)]> create database Teacher;
MariaDB [(none)]> show databases;
MariaDB [(none)]> drop database Teacher;

@ table 생성
MariaDB [(none)]> create database School;

MariaDB [(none)]> use School;
Database changed

MariaDB [School]> show tables;
Empty set (0.000 sec)

MariaDB [School]> create table Student ( Name varchar(8),Date int(4), Phone int(11) );

 

 

 

MariaDB [School]> desc Student;

 

desc : Description 묘사

 

 

@ Alter table
MariaDB [School]> alter table Student add Address varchar(20);

@ Date 필드 앞에 생성하기
MariaDB [School]> alter table Student add Age int(3) after Date;

@ Age2 필드를 첫번째 필드로 생성하기
MariaDB [School]> alter table Student add Age2 int first;

@ Address2, Address3 여러 필드를 생성하기
MariaDB [School]> alter table Student add ( Address2 varchar(20) , Address3 varchar(20) );

 

 

 

@ after . first 연습

MariaDB [School]> alter table Student modify Name varchar(8) first;
MariaDB [School]> alter table Student modify Age2 int after Age;
MariaDB [School]> alter table Student drop Address3;

 

 

@ change로 필드명. 타입 변경하기
MariaDB [School]> alter table Student change Age2 Age2 varchar(8);

@ Age2, Address2 삭제
MariaDB [School]> alter table Student drop Age2;
MariaDB [School]> alter table Student drop Address2;

@ insert ~ values (필드의 순서대로)
MariaDB [School]> insert into Student values ('Kim', 2024, 25, 12345678, 'Daegu');
MariaDB [School]> insert into Student (Name , Date, Address) values ('Lee',2025,'Seoul');
MariaDB [School]> insert into Student values ('Park',2022,29,12341234,'Busan');

 

 

 

@ update ~ set 

MariaDB [School]> update Student set Date = 2025;
MariaDB [School]> update Student set Name = 'Choi' where Name = 'Park';
MariaDB [School]> update Student set Name = 'Kim', Age = 29 where Address='Seou';

@ delete from ~ where
MariaDB [School]> delete from Student where Address='Seoul';
MariaDB [School]> delete from Student;

@ drop table 
MariaDB [School]> drop table Student;