MySQL 사용법 (요약)
이강성
2000.1.26
시작하기
형식 : mysql -h hostname -u user_name -p DBname
hostname 의 default : localhost user_name의 default : login name
예1) mysql -u guest # user가 guest이고 password가 없을 경우 (localhost)
예1) mysql -h sr.kwangwoon.ac.kr -u guest # user가 guest이고 password가 없을 경우
예2) mysql -u guest -p # password를 입력해야 함
Enter password:********
예3) mysql -u guest pythonDB
참고) 컴퓨터 sr에서 mysql을 이용하여 연습을 하려면 여기서 사용하는 모든 데이터베이스 명 대신에
test를 사용하라. 사용자는 누구라도 되고, 테이블을 만들고 검색하고 삭제할 수 있다.
암호는 주어져 있지 않다.
실행예: mysql -u guest test
끝내기
mysql> QUIT
mysql> Ctrl-D
*mysql> 은 프롬프트임
변경:
mysql -u root -p
Enter password:*****
mysql> use mysql
mysql> update user set Password=PASSWORD('password') where user='userid';
mysql> flush privileges;
버전과 날짜 보기:
* 명령에 대소문자 구분은 없다 (case insensitive). mysql> 은 프롬프트임.
mysql> SELECT VERSION(), CURRENT_DATE;
+--------------+--------------+
| version() | CURRENT_DATE |
+--------------+--------------+
| 3.22.20a-log | 1999-03-19 |
+--------------+--------------+
1 row in set (0.01 sec)
mysql>
계산기로 사용하기:
mysql> SELECT SIN(PI()/4), (4+1)*5;
+-------------+---------+
| SIN(PI()/4) | (4+1)*5 |
+-------------+---------+
| 0.707107 | 25 |
+-------------+---------+
여러 명령 한줄에 입력하기:
mysql> SELECT VERSION(); SELECT NOW();
+--------------+
| version() |
+--------------+
| 3.22.20a-log |
+--------------+
+---------------------+
| NOW() |
+---------------------+
| 1999-03-19 00:15:33 |
+---------------------+
여려줄에 한 명령 입력하기:
mysql> SELECT
-> USER()
-> ,
-> CURRENT_DATE;
+--------------------+--------------+
| USER() | CURRENT_DATE |
+--------------------+--------------+
| joesmith@localhost | 1999-03-18 |
+--------------------+--------------+
데이터베이스 보기 :
SHOW DATABASES;
+----------+
| Database |
+----------+
| mysql |
| python |
| test |
+----------+
사용할 데이터베이스 선택하기 :
USE test
관리자로 하여금 지정된 사용자만 DB를 접근하도록 하기 :
GRANT ALL ON dbname.* TO your_mysql_name; 새로운 데이터베이스 만들기:
CREATE DATABASE menagerie;
관리자가 해주던지 아니면 본인이 해야한다(허가권이 있다면).
사용할 데이터베이스 선택 :
USE menagerie
mysql을 호출할 때 db선택하기 :
mysql -h host -u user -p menagerie
데이터베이스 없애기: (한번에 모든 것을 날려 버리므로 조심해서 사용할 것)
DROP DATABASE database_name
테이블 보기 :
SHOW TABLES;
Empty set (0.00 sec)
테이블 만들기 :
CREATE TABLE pet (
-> name VARCHAR(20),
-> owner VARCHAR(20),
-> species VARCHAR(20),
-> sex CHAR(1),
-> birth DATE,
-> death DATE);
테이블 다시 보기:
mysql> SHOW TABLES;
+---------------------+
| Tables in menagerie |
+---------------------+
| pet |
+---------------------+
테이블 확인하기:
mysql> DESCRIBE pet;
+---------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| name | varchar(20) | YES | | NULL | |
| owner | varchar(20) | YES | | NULL | |
| species | varchar(20) | YES | | NULL | |
| sex | char(1) | YES | | NULL | |
| birth | date | YES | | NULL | |
| death | date | YES | | NULL | |
+---------+-------------+------+-----+---------+-------+
테이블 없애기:
mysql> DROP table table_name;
테이블에 입력할 정보가 다음과 같다고 하자:
name
| owner
| species
| sex
| birth
| death
|
Fluffy
| Harold
| cat
| f
| 1993-02-04
|
|
Claws
| Gwen
| cat
| m
| 1994-03-17
|
|
Buffy
| Harold
| dog
| f
| 1989-05-13
|
|
Fang
| Benny
| dog
| m
| 1990-08-27
|
|
Bowser
| Diane
| dog
| m
| 1998-08-31
| 1995-07-29
|
Chirpy
| Gwen
| bird
| f
| 1998-09-11
|
|
Whistler
| Gwen
| bird
|
| 1997-12-09
|
|
Slim
| Benny
| snake
| m
| 1996-04-29
|
|
텍스트 파일에 정보가 있다면 쉽게 일괄적으로 테이블에 입력할 수 있다. 각 레코드는 한 라인에 입력되며, 각 필드는 탭으로 구분되어야 하고, NULL인 필드는 \N이 입력되어야 한다. 예:
Whistler
| Gwen
| bird
| \N
| 1997-12-09
| \N
|
이와 같은 정보가 'pet.txt' 파일에 저장되어 있다고 한다면, 다음의 명령으로 일괄적으로 읽어들일 수 있다.
mysql> LOAD DATA LOCAL INFILE "pet.txt" INTO TABLE pet;
한번에 한 레코드씩 입력하려면 다음과 같은 코맨드라인 명령을 쓴다.
mysql> INSERT INTO pet
-> VALUES ('Puffball','Diane','hamster','f','1999-03-30',NULL);
이 경우 값이 없으면 NULL을 사용한다. (\N는 아님)
SELECT 문을 이용한다:
SELECT what_to_select
FROM which_table
WHERE conditions_to_satisfy
전체 데이터 선택하기
mysql> SELECT * FROM pet;
+----------+--------+---------+------+------------+------------+
| name | owner | species | sex | birth | death |
+----------+--------+---------+------+------------+------------+
| Fluffy | Harold | cat | f | 1993-02-04 | NULL |
| Claws | Gwen | cat | m | 1994-03-17 | NULL |
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
| Fang | Benny | dog | m | 1990-08-27 | NULL |
| Bowser | Diane | dog | m | 1998-08-31 | 1995-07-29 |
| Chirpy | Gwen | bird | f | 1998-09-11 | NULL |
| Whistler | Gwen | bird | NULL | 1997-12-09 | NULL |
| Slim | Benny | snake | m | 1996-04-29 | NULL |
| Puffball | Diane | hamster | f | 1999-03-30 | NULL |
+----------+--------+---------+------+------------+------------+
정보 갱신하기: Bowser의 생일을 1998년에서 1989로 수정하려면,
mysql> UPDATE pet SET birth = "1989-08-31" WHERE name = "Bowser";
행 선택하여 출력하기:
mysql> SELECT * FROM pet WHERE name = "Bowser";
+--------+-------+---------+------+------------+------------+
| name | owner | species | sex | birth | death |
+--------+-------+---------+------+------------+------------+
| Bowser | Diane | dog | m | 1989-08-31 | 1995-07-29 |
+--------+-------+---------+------+------------+------------+
mysql> SELECT * FROM pet WHERE birth >= "1998-1-1";
+----------+-------+---------+------+------------+-------+
| name | owner | species | sex | birth | death |
+----------+-------+---------+------+------------+-------+
| Chirpy | Gwen | bird | f | 1998-09-11 | NULL |
| Puffball | Diane | hamster | f | 1999-03-30 | NULL |
+----------+-------+---------+------+------------+-------+
mysql> SELECT * FROM pet WHERE species = "dog" AND sex = "f";
+-------+--------+---------+------+------------+-------+
| name | owner | species | sex | birth | death |
+-------+--------+---------+------+------------+-------+
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
+-------+--------+---------+------+------------+-------+
mysql> SELECT * FROM pet WHERE species = "snake" OR species = "bird";
+----------+-------+---------+------+------------+-------+
| name | owner | species | sex | birth | death |
+----------+-------+---------+------+------------+-------+
| Chirpy | Gwen | bird | f | 1998-09-11 | NULL |
| Whistler | Gwen | bird | NULL | 1997-12-09 | NULL |
| Slim | Benny | snake | m | 1996-04-29 | NULL |
+----------+-------+---------+------+------------+-------+
mysql> SELECT * FROM pet WHERE (species = "cat" AND sex = "m")
-> OR (species = "dog" AND sex = "f");
+-------+--------+---------+------+------------+-------+
| name | owner | species | sex | birth | death |
+-------+--------+---------+------+------------+-------+
| Claws | Gwen | cat | m | 1994-03-17 | NULL |
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
+-------+--------+---------+------+------------+-------+
열 선택하여 출력하기
mysql> SELECT name, birth FROM pet;
+----------+------------+
| name | birth |
+----------+------------+
| Fluffy | 1993-02-04 |
| Claws | 1994-03-17 |
| Buffy | 1989-05-13 |
| Fang | 1990-08-27 |
| Bowser | 1989-08-31 |
| Chirpy | 1998-09-11 |
| Whistler | 1997-12-09 |
| Slim | 1996-04-29 |
| Puffball | 1999-03-30 |
+----------+------------+
mysql> SELECT owner FROM pet;
+--------+
| owner |
+--------+
| Harold |
| Gwen |
| Harold |
| Benny |
| Diane |
| Gwen |
| Gwen |
| Benny |
| Diane |
+--------+
mysql> SELECT DISTINCT owner FROM pet;
+--------+
| owner |
+--------+
| Benny |
| Diane |
| Gwen |
| Harold |
+--------+
mysql> SELECT name, species, birth FROM pet
-> WHERE species = "dog" OR species = "cat";
+--------+---------+------------+
| name | species | birth |
+--------+---------+------------+
| Fluffy | cat | 1993-02-04 |
| Claws | cat | 1994-03-17 |
| Buffy | dog | 1989-05-13 |
| Fang | dog | 1990-08-27 |
| Bowser | dog | 1989-08-31 |
+--------+---------+------------+
정렬하기
mysql> SELECT name, birth FROM pet ORDER BY birth;
+----------+------------+
| name | birth |
+----------+------------+
| Buffy | 1989-05-13 |
| Bowser | 1989-08-31 |
| Fang | 1990-08-27 |
| Fluffy | 1993-02-04 |
| Claws | 1994-03-17 |
| Slim | 1996-04-29 |
| Whistler | 1997-12-09 |
| Chirpy | 1998-09-11 |
| Puffball | 1999-03-30 |
+----------+------------+
mysql> SELECT name, birth FROM pet ORDER BY birth DESC;
+----------+------------+
| name | birth |
+----------+------------+
| Puffball | 1999-03-30 |
| Chirpy | 1998-09-11 |
| Whistler | 1997-12-09 |
| Slim | 1996-04-29 |
| Claws | 1994-03-17 |
| Fluffy | 1993-02-04 |
| Fang | 1990-08-27 |
| Bowser | 1989-08-31 |
| Buffy | 1989-05-13 |
+----------+------------+
mysql> SELECT name, species, birth FROM pet ORDER BY species, birth DESC;
+----------+---------+------------+
| name | species | birth |
+----------+---------+------------+
| Chirpy | bird | 1998-09-11 |
| Whistler | bird | 1997-12-09 |
| Claws | cat | 1994-03-17 |
| Fluffy | cat | 1993-02-04 |
| Fang | dog | 1990-08-27 |
| Bowser | dog | 1989-08-31 |
| Buffy | dog | 1989-05-13 |
| Puffball | hamster | 1999-03-30 |
| Slim | snake | 1996-04-29 |
+----------+---------+------------+
날짜계산하기
mysql> SELECT name, (TO_DAYS(NOW())-TO_DAYS(birth))/365 FROM pet;
+----------+-------------------------------------+
| name | (TO_DAYS(NOW())-TO_DAYS(birth))/365 |
+----------+-------------------------------------+
| Fluffy | 6.15 |
| Claws | 5.04 |
| Buffy | 9.88 |
| Fang | 8.59 |
| Bowser | 9.58 |
| Chirpy | 0.55 |
| Whistler | 1.30 |
| Slim | 2.92 |
| Puffball | 0.00 |
+----------+-------------------------------------+
mysql> SELECT name, (TO_DAYS(NOW())-TO_DAYS(birth))/365 AS age
-> FROM pet ORDER BY name;
+----------+------+
| name | age |
+----------+------+
| Bowser | 9.58 |
| Buffy | 9.88 |
| Chirpy | 0.55 |
| Claws | 5.04 |
| Fang | 8.59 |
| Fluffy | 6.15 |
| Puffball | 0.00 |
| Slim | 2.92 |
| Whistler | 1.30 |
+----------+------+
mysql> SELECT name, (TO_DAYS(NOW())-TO_DAYS(birth))/365 AS age
-> FROM pet ORDER BY age;
+----------+------+
| name | age |
+----------+------+
| Puffball | 0.00 |
| Chirpy | 0.55 |
| Whistler | 1.30 |
| Slim | 2.92 |
| Claws | 5.04 |
| Fluffy | 6.15 |
| Fang | 8.59 |
| Bowser | 9.58 |
| Buffy | 9.88 |
+----------+------+
mysql> SELECT name, birth, death, (TO_DAYS(death)-TO_DAYS(birth))/365 AS age
-> FROM pet WHERE death IS NOT NULL ORDER BY age;
+--------+------------+------------+------+
| name | birth | death | age |
+--------+------------+------------+------+
| Bowser | 1989-08-31 | 1995-07-29 | 5.91 |
+--------+------------+------------+------+
DATE에서 해, 달, 일의 정보를 꺼내려면, YEAR(), MONTH(), DAYOFMONTH()를 이용한다.
mysql> SELECT name, birth, MONTH(birth) FROM pet;
+----------+------------+--------------+
| name | birth | MONTH(birth) |
+----------+------------+--------------+
| Fluffy | 1993-02-04 | 2 |
| Claws | 1994-03-17 | 3 |
| Buffy | 1989-05-13 | 5 |
| Fang | 1990-08-27 | 8 |
| Bowser | 1989-08-31 | 8 |
| Chirpy | 1998-09-11 | 9 |
| Whistler | 1997-12-09 | 12 |
| Slim | 1996-04-29 | 4 |
| Puffball | 1999-03-30 | 3 |
+----------+------------+--------------+
5월에 태어난 동물을 출력하려면:
mysql> SELECT name, birth FROM pet WHERE MONTH(birth) = 5;
+-------+------------+
| name | birth |
+-------+------------+
| Buffy | 1989-05-13 |
+-------+------------+
패턴 매칭
'%'는 (0을 포함한) 임의의 수의 문자와 매칭한다. 'b'로 시작하는 이름의 동물을 찾으려면,
mysql> SELECT * FROM pet WHERE name LIKE "b%";
+--------+--------+---------+------+------------+------------+
| name | owner | species | sex | birth | death |
+--------+--------+---------+------+------------+------------+
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
| Bowser | Diane | dog | m | 1989-08-31 | 1995-07-29 |
+--------+--------+---------+------+------------+------------+
'fy'로 끝나는 이름의 동물은,
mysql> SELECT * FROM pet WHERE name LIKE "%fy";
+--------+--------+---------+------+------------+-------+
| name | owner | species | sex | birth | death |
+--------+--------+---------+------+------------+-------+
| Fluffy | Harold | cat | f | 1993-02-04 | NULL |
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
+--------+--------+---------+------+------------+-------+
'w'가 있는 이름의 동물은,
mysql> SELECT * FROM pet WHERE name LIKE "%w%";
+----------+-------+---------+------+------------+------------+
| name | owner | species | sex | birth | death |
+----------+-------+---------+------+------------+------------+
| Claws | Gwen | cat | m | 1994-03-17 | NULL |
| Bowser | Diane | dog | m | 1989-08-31 | 1995-07-29 |
| Whistler | Gwen | bird | NULL | 1997-12-09 | NULL |
+----------+-------+---------+------+------------+------------+
꼭 다섯자로 구성된 이름의 동물은,
mysql> SELECT * FROM pet WHERE name LIKE "_____";
+-------+--------+---------+------+------------+-------+
| name | owner | species | sex | birth | death |
+-------+--------+---------+------+------------+-------+
| Claws | Gwen | cat | m | 1994-03-17 | NULL |
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
+-------+--------+---------+------+------------+-------+
확장된 정규식
- '.'는 임의의 한자와 매치
- '[abc] 는 'a' 또는 'b' 또는 'c'
- '*'는 0이상의 임의의 수의 앞선 문자와 매치 'x*'는 임의의 수의 'x'와 매치. [0-9]*는 임의의 수의 숫자와, '.*' 는 임의의 문자와 매치
- 대소문자를 구별함 (case sensitive)
- 테스트되는 임의의 어떤 부분에서 매치되면 됨 (SQL패턴 매치는 전체가 다 매치되어야함)
- 시작과 끝을 매치하기 위하여 '^' '$'를 사용한다.
'b'혹은 'B'로 시작하는 이름:
mysql> SELECT * FROM pet WHERE name REGEXP "^[bB]";
+--------+--------+---------+------+------------+------------+
| name | owner | species | sex | birth | death |
+--------+--------+---------+------+------------+------------+
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
| Bowser | Diane | dog | m | 1989-08-31 | 1995-07-29 |
+--------+--------+---------+------+------------+------------+
마지막에 `fy' 로 끝나는 이름:
mysql> SELECT * FROM pet WHERE name REGEXP "fy$";
+--------+--------+---------+------+------------+-------+
| name | owner | species | sex | birth | death |
+--------+--------+---------+------+------------+-------+
| Fluffy | Harold | cat | f | 1993-02-04 | NULL |
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
+--------+--------+---------+------+------------+-------+
`w'를 포함하는 이름:
mysql> SELECT * FROM pet WHERE name REGEXP "[wW]";
+----------+-------+---------+------+------------+------------+
| name | owner | species | sex | birth | death |
+----------+-------+---------+------+------------+------------+
| Claws | Gwen | cat | m | 1994-03-17 | NULL |
| Bowser | Diane | dog | m | 1989-08-31 | 1995-07-29 |
| Whistler | Gwen | bird | NULL | 1997-12-09 | NULL |
+----------+-------+---------+------+------------+------------+
다섯 문자로 이루어진 이름:
mysql> SELECT * FROM pet WHERE name REGEXP "^.....$";
+-------+--------+---------+------+------------+-------+
| name | owner | species | sex | birth | death |
+-------+--------+---------+------+------------+-------+
| Claws | Gwen | cat | m | 1994-03-17 | NULL |
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
+-------+--------+---------+------+------------+-------+
`{n}' 연산자 (repeat-n-times)를 사용하여 아래와 같이 쓸 수도 있음:
mysql> SELECT * FROM pet WHERE name REGEXP "^.{5}$";
+-------+--------+---------+------+------------+-------+
| name | owner | species | sex | birth | death |
+-------+--------+---------+------+------------+-------+
| Claws | Gwen | cat | m | 1994-03-17 | NULL |
| Buffy | Harold | dog | f | 1989-05-13 | NULL |
+-------+--------+---------+------+------------+-------+
행의 수 세기
전체 엔트리 수 세기:
mysql> SELECT COUNT(*) FROM pet;
+----------+
| COUNT(*) |
+----------+
| 9 |
+----------+
주인이 가지고 있는 동물의 수 세기:
mysql> SELECT owner, COUNT(*) FROM pet GROUP BY owner;
+--------+----------+
| owner | COUNT(*) |
+--------+----------+
| Benny | 2 |
| Diane | 2 |
| Gwen | 3 |
| Harold | 2 |
+--------+----------+
종별 수:
mysql> SELECT species, COUNT(*) FROM pet GROUP BY species;
+---------+----------+
| species | COUNT(*) |
+---------+----------+
| bird | 2 |
| cat | 2 |
| dog | 3 |
| hamster | 1 |
| snake | 1 |
+---------+----------+
성별 수:
mysql> SELECT sex, COUNT(*) FROM pet GROUP BY sex;
+------+----------+
| sex | COUNT(*) |
+------+----------+
| NULL | 1 |
| f | 4 |
| m | 4 |
+------+----------+
종 및 성별 수:
mysql> SELECT species, sex, COUNT(*) FROM pet GROUP BY species, sex;
+---------+------+----------+
| species | sex | COUNT(*) |
+---------+------+----------+
| bird | NULL | 1 |
| bird | f | 1 |
| cat | f | 1 |
| cat | m | 1 |
| dog | f | 1 |
| dog | m | 2 |
| hamster | f | 1 |
| snake | m | 1 |
+---------+------+----------+
개와 고양이에 대해서만 적용:
mysql> SELECT species, sex, COUNT(*) FROM pet
-> WHERE species = "dog" OR species = "cat"
-> GROUP BY species, sex;
+---------+------+----------+
| species | sex | COUNT(*) |
+---------+------+----------+
| cat | f | 1 |
| cat | m | 1 |
| dog | f | 1 |
| dog | m | 2 |
+---------+------+----------+
알려진 성별에 대해서만 성별 동물의 수:
mysql> SELECT species, sex, COUNT(*) FROM pet
-> WHERE sex IS NOT NULL
-> GROUP BY species, sex;
+---------+------+----------+
| species | sex | COUNT(*) |
+---------+------+----------+
| bird | f | 1 |
| cat | f | 1 |
| cat | m | 1 |
| dog | f | 1 |
| dog | m | 2 |
| hamster | f | 1 |
| snake | m | 1 |
+---------+------+----------+
테이블 하나 더 만들기:
mysql> CREATE TABLE event (
-> name VARCHAR(20),
-> date DATE,
-> type VARCHAR(15),
-> remark VARCHAR(255));
파일 'event.txt'
Fluffy
| 1995-05-15
| litter
| 4 kittens, 3 female, 1 male
|
Buffy
| 1993-06-23
| litter
| 5 puppies, 2 female, 3 male
|
Buffy
| 1994-06-19
| litter
| 3 puppies, 3 female
|
Chirpy
| 1999-03-21
| vet
| needed beak straightened
|
Slim
| 1997-08-03
| vet
| broken rib
|
Bowser
| 1991-10-12
| kennel
|
|
Fang
| 1991-10-12
| kennel
|
|
Fang
| 1998-08-28
| birthday
| Gave him a new chew toy
|
Claws
| 1998-03-17
| birthday
| Gave him a new flea collar
|
Whistler
| 1998-12-09
| birthday
| First birthday
|
데이터 읽어들이기:
mysql> LOAD DATA LOCAL INFILE "event.txt" INTO TABLE event;
출산 때의 동물의 나이를 계산 (JOIN):
mysql> SELECT pet.name, (TO_DAYS(date) - TO_DAYS(birth))/365 AS age, remark
-> FROM pet, event
-> WHERE pet.name = event.name AND type = "litter";
+--------+------+-----------------------------+
| name | age | remark |
+--------+------+-----------------------------+
| Fluffy | 2.27 | 4 kittens, 3 female, 1 male |
| Buffy | 4.12 | 5 puppies, 2 female, 3 male |
| Buffy | 5.10 | 3 puppies, 3 female |
+--------+------+-----------------------------+
짝찾아보기 (JOINing itself):
mysql> SELECT p1.name, p1.sex, p2.name, p2.sex, p1.species
-> FROM pet AS p1, pet AS p2
-> WHERE p1.species = p2.species AND p1.sex = "f" AND p2.sex = "m";
+--------+------+--------+------+---------+
| name | sex | name | sex | species |
+--------+------+--------+------+---------+
| Fluffy | f | Claws | m | cat |
| Buffy | f | Fang | m | dog |
| Buffy | f | Bowser | m | dog |
+--------+------+--------+------+---------+
CREATE TABLE shop (
article INT(4) UNSIGNED ZEROFILL DEFAULT '0000' NOT NULL,
dealer CHAR(20) DEFAULT '' NOT NULL,
price DOUBLE(16,2) DEFAULT '0.00' NOT NULL,
PRIMARY KEY(article, dealer));
INSERT INTO shop VALUES
(1,'A',3.45),(1,'B',3.99),(2,'A',10.99),(3,'B',1.45),(3,'C',1.69),
(3,'D',1.25),(4,'D',19.95);
전체 데이터 예는:
SELECT * FROM shop
+---------+--------+-------+
| article | dealer | price |
+---------+--------+-------+
| 0001 | A | 3.45 |
| 0001 | B | 3.99 |
| 0002 | A | 10.99 |
| 0003 | B | 1.45 |
| 0003 | C | 1.69 |
| 0003 | D | 1.25 |
| 0004 | D | 19.95 |
+---------+--------+-------+
최대 아이템 수는?
SELECT MAX(article) AS article FROM shop
+---------+
| article |
+---------+
| 4 |
+---------+
가장 비싼 항목의 번호, 판매자, 가격?
SELECT article, dealer, price
FROM shop
WHERE price=(SELECT MAX(price) FROM shop)
각 항목의 최고 가격은?
SELECT article, MAX(price) AS price
FROM shop
GROUP BY article
+---------+-------+
| article | price |
+---------+-------+
| 0001 | 3.99 |
| 0002 | 10.99 |
| 0003 | 1.69 |
| 0004 | 19.95 |
+---------+-------+
각 항목에 대하여 가장 비싼 가격의 딜러를 찾아라!
SELECT article, dealer, price
FROM shop s1
WHERE price=(SELECT MAX(s2.price)
FROM shop s2
WHERE s1.article = s2.article)
항목 삭제하기 (DELETE)
문법 : DELETE FROM tbl_name [WHERE where_condition] [LIMIT rows]
CREATE TABLE persons (
id SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT,
name CHAR(60) NOT NULL,
PRIMARY KEY (id)
);
CREATE TABLE shirts (
id SMALLINT UNSIGNED NOT NULL AUTO_INCREMENT,
style ENUM('t-shirt', 'polo', 'dress') NOT NULL,
color ENUM('red', 'blue', 'orange', 'white', 'black') NOT NULL,
owner SMALLINT UNSIGNED NOT NULL REFERENCES persons,
PRIMARY KEY (id)
);
INSERT INTO persons VALUES (NULL, 'Antonio Paz');
INSERT INTO shirts VALUES
(NULL, 'polo', 'blue', LAST_INSERT_ID()),
(NULL, 'dress', 'white', LAST_INSERT_ID()),
(NULL, 't-shirt', 'blue', LAST_INSERT_ID());
INSERT INTO persons VALUES (NULL, 'Lilliana Angelovska');
INSERT INTO shirts VALUES
(NULL, 'dress', 'orange', LAST_INSERT_ID()),
(NULL, 'polo', 'red', LAST_INSERT_ID()),
(NULL, 'dress', 'blue', LAST_INSERT_ID()),
(NULL, 't-shirt', 'white', LAST_INSERT_ID());
SELECT * FROM persons;
+----+---------------------+
| id | name |
+----+---------------------+
| 1 | Antonio Paz |
| 2 | Lilliana Angelovska |
+----+---------------------+
SELECT * FROM shirts;
+----+---------+--------+-------+
| id | style | color | owner |
+----+---------+--------+-------+
| 1 | polo | blue | 1 |
| 2 | dress | white | 1 |
| 3 | t-shirt | blue | 1 |
| 4 | dress | orange | 2 |
| 5 | polo | red | 2 |
| 6 | dress | blue | 2 |
| 7 | t-shirt | white | 2 |
+----+---------+--------+-------+
SELECT s.* FROM persons p, shirts s
WHERE p.name LIKE 'Lilliana%'
AND s.owner = p.id
AND s.color <> 'white';
+----+-------+--------+-------+
| id | style | color | owner |
+----+-------+--------+-------+
| 4 | dress | orange | 2 |
| 5 | polo | red | 2 |
| 6 | dress | blue | 2 |
+----+-------+--------+-------+
테이블 이름 바꾸기
t1에서 t2로 이름 바꾸기
mysql> CREATE TABLE t1 (a INTEGER,b CHAR(10));
mysql> ALTER TABLE t1 RENAME t2;
컬럼의 형 바꾸기
테이블 t2의 컬럼 a를 INTEGER에서 TINYINT NOT NULL 형으로 전환하기
mysql> ALTER TABLE t2 MODIFY a TINYINT NOT NULL;
컬럼의 길이 바꾸기
테이블 t2의 컬럼 b CHAR(10)을 c CHAR(20)으로 길이와 이름 바꾸기
mysql> ALTER TABLE t2 CHANGE b c CHAR(20);
새 컬럼 추가하기
timestamp란 컬럼을 t2에 추가하기
mysql> ALTER TABLE t2 ADD d TIMESTAMP;
인덱스 컬럼 만들기 / primary key 설정하기
t2에 컬럼 d의 인덱스를 추가하기, 컬럼 a를 주 키로 설정한다.
mysql> ALTER TABLE t2 ADD INDEX (d), ADD PRIMARY KEY (a);
컬럼 없애기
테이블 t2에서 컬럼 c를 없앤다.
mysql> ALTER TABLE t2 DROP COLUMN c;
새 컬럼 추가하기
테이블 t2에 INT UNSIGNED NOT NULL AUTO_INCREMENT 형 컬럼 c를 새로 만들기
mysql> ALTER TABLE t2 ADD c INT UNSIGNED NOT NULL AUTO_INCREMENT;
테이블 없애기
mysql> DROP TABLE table_name
언어 참조
스트링
Escape sequences
\0 An ASCII 0 (NUL) character.
\n A newline character.
\t A tab character.
\r A carriage return character.
\b A backspace character.
\' A single quote (`'') character.
\" A double quote (`"') character.
\\ A backslash (`\') character.
\% A `%' character. This is used to search for literal instances of `%' in contexts
where `%' would otherwise be interpreted as a wildcard character.
\_ A `_' character. This is used to search for literal instances of `_' in contexts
where `_' would otherwise be interpreted as a wildcard character.
mysql> SELECT 'hello', '"hello"', '""hello""', 'hel''lo', '\'hello';
+-------+---------+-----------+--------+--------+
| hello | "hello" | ""hello"" | hel'lo | 'hello |
+-------+---------+-----------+--------+--------+
mysql> SELECT "hello", "'hello'", "''hello''", "hel""lo", "\"hello";
+-------+---------+-----------+--------+--------+
| hello | 'hello' | ''hello'' | hel"lo | "hello |
+-------+---------+-----------+--------+--------+
mysql> SELECT "This\nIs\nFour\nlines";
+--------------------+
| This
Is
Four
lines |
+--------------------+
숫자
정수형 (1221, 0, -32), 부동소숫점형 (3.4, -23.45e+10, 148.00), 16진수(0x23fc)
Column Types
Numeric types
Column type
| Storage required
|
TINYINT
| 1 byte
|
SMALLINT
| 2 bytes
|
MEDIUMINT
| 3 bytes
|
INT
| 4 bytes
|
INTEGER
| 4 bytes
|
BIGINT
| 8 bytes
|
FLOAT(X)
| 4 if X <= 24 or 8 if 25 <= X <= 53
|
FLOAT
| 4 bytes
|
DOUBLE
| 8 bytes
|
DOUBLE PRECISION
| 8 bytes
|
REAL
| 8 bytes
|
DECIMAL(M,D)
| M bytes (D+2, if M < D)
|
NUMERIC(M,D)
| M bytes (D+2, if M < D)
|
Date and time types
Column type
| Storage required
|
DATE
| 3 bytes
|
DATETIME
| 8 bytes
|
TIMESTAMP
| 4 bytes
|
TIME
| 3 bytes
|
YEAR
| 1 byte
|
date, time이 값의 범위를 벋어날 경우는 zero value를 갖는다.
Column type
| ``Zero'' value
|
DATETIME
| '0000-00-00 00:00:00'
|
DATE
| '0000-00-00'
|
TIMESTAMP
| 00000000000000 (length depends on display size)
|
TIME
| '00:00:00'
|
YEAR
| 0000
|
Timestamp format
Column type
| Display format
|
TIMESTAMP(14)
| YYYYMMDDHHMMSS
|
TIMESTAMP(12)
| YYMMDDHHMMSS
|
TIMESTAMP(10)
| YYMMDDHHMM
|
TIMESTAMP(8)
| YYYYMMDD
|
TIMESTAMP(6)
| YYMMDD
|
TIMESTAMP(4)
| YYMM
|
TIMESTAMP(2)
| YY
|
String types
Column type
| Storage required
|
CHAR(M)
| M bytes, 1 <= M <= 255
|
VARCHAR(M)
| L+1 bytes, where L <= M and 1 <= M <= 255
|
TINYBLOB, TINYTEXT
| L+1 bytes, where L < 2^8
|
BLOB, TEXT
| L+2 bytes, where L < 2^16
|
MEDIUMBLOB, MEDIUMTEXT
| L+3 bytes, where L < 2^24
|
LONGBLOB, LONGTEXT
| L+4 bytes, where L < 2^32
|
ENUM('value1','value2',...)
| 1 or 2 bytes, depending on the number of enumeration values (65535 values maximum)
|
SET('value1','value2',...)
| 1, 2, 3, 4 or 8 bytes, depending on the number of set members (64 members maximum)
|
기억 용량 비교
Value
| CHAR(4)
| Storage required
| VARCHAR(4)
| Storage required
|
''
| ' '
| 4 bytes
| ''
| 1 byte
|
'ab'
| 'ab '
| 4 bytes
| 'ab'
| 3 bytes
|
'abcd'
| 'abcd'
| 4 bytes
| 'abcd'
| 5 bytes
|
'abcdefgh'
| 'abcd'
| 4 bytes
| 'abcd'
| 5 bytes
|
* BLOB 는 case-sensitive, TEXT는 case-insensitive
인덱스
적절한 인덱스의 사용은 SELECT문의 성능을 크게 향상시켜준다. 최대 16개까지의 인덱스를 갖는다. 최대 인덱스 길이는 256바이트이다. CHAR과 VARCHAR에 대해서 앞 문자열을 대상으로 인덱스 할 수 있다. BLOB와 TEXT에 대해서 앞문자열을 사용하는 것은 인덱스 할 때 필수이다.
mysql> CREATE TABLE test (
name CHAR(200) NOT NULL,
KEY index_name (name(10)));
복수개 컬럼에 대해서 인덱스를 만들 수 있다. 최대 15개 컬럼을 사용할 수 있다.
mysql> CREATE TABLE test (
id INT NOT NULL,
last_name CHAR(30) NOT NULL,
first_name CHAR(30) NOT NULL,
PRIMARY KEY (id),
INDEX name (last_name,first_name));
name인덱스의 사용예:
mysql> SELECT * FROM test WHERE last_name="Widenius";
mysql> SELECT * FROM test WHERE last_name="Widenius"
AND first_name="Michael";
mysql> SELECT * FROM test WHERE last_name="Widenius"
AND (first_name="Michael" OR first_name="Monty");
mysql> SELECT * FROM test WHERE last_name="Widenius"
AND first_name >="M" AND first_name < "N";
연산자
다음의 연산자는 select문에서 사용가능하다.
산술 연산자
+, -, *, /, MOD(a,b) : a를 b로 나눈 나머지
비트 연산자
|, &, <<, >>, ~, BIT_COUNT(N) : N의 설정된 비트 수
논리 연산자
!, ||, &&,
비교 연산자
=, >, <, >=, <=, <> (!=),
<=> (Null safe equal),
IS NULL, IS NOT NULL,
between a and b
expr IN (value, ...), expr NOT IN (value, ...)
ISNULL(expr), COALESCE(list), INTERVAL(N,N1,N2,N3,...)
mysql> select 1 <=> 1, NULL <=> NULL, 1 <=> NULL;
-> 1 1 0
mysql> select 1 BETWEEN 2 AND 3;
-> 0
mysql> select 'b' BETWEEN 'a' AND 'c';
-> 1
mysql> select 2 BETWEEN 2 AND '3';
-> 1
mysql> select 2 BETWEEN 2 AND 'x-3';
-> 0
mysql> select 2 IN (0,3,5,'wefwf');
-> 0
mysql> select 'wefwf' IN (0,3,5,'wefwf');
-> 1
.......
| 
상속된 Public property 보기