sql mysql정리

Posted 2021-05-13

CREATE DATABASE hello_world_db; 
DROP DATABASE hello_world_db; 

USE dog_walking_app;
SELECT database();

CREATE TABLE cats
  (
    name VARCHAR(100),
    age INT
  );
  
  SHOW TABLES;
  SHOW COLUMNS FROM cats; 
  or DESC cats;
  
DROP TABLE cats;

INSERT INTO cats(name, age) VALUES ('Jetson', 7);

SELECT * FROM cats;

INSERT INTO cats(name, age)
    VALUES ('Peanut', 2), ('Butter', 4), ('Jelly', 7);
    
    
Escape the quotes with a backslash: "This text has \"quotes\" in it" or 'This text has \'quotes\' in it'
Alternate single and double quotes: "This text has 'quotes' in it" or 'This text has "quotes" in it'

ALTER TABLE cats MODIFY name VARCHAR(50);

-- Change Error to Warning
SET @@global.sql_mode= '';

-- NOT NULL CASE
CREATE TABLE cats2
  (
    name VARCHAR(100) NOT NULL,
    age INT NOT NULL
  );
경고 메시지 확인 
SHOW WARNINGS;

-- Default Value 
CREATE TABLE cats3
  (
    name VARCHAR(20) DEFAULT 'no name provided',
    age INT DEFAULT 99
  );

-- Default Value and Not Null
CREATE TABLE cats4
  (
    name VARCHAR(20) NOT NULL DEFAULT 'unnamed',
    age INT NOT NULL DEFAULT 99
  );


--- with a primary key
CREATE TABLE unique_cats
  (
    cat_id INT NOT NULL,
    name VARCHAR(100),
    age INT,
    PRIMARY KEY (cat_id)
  );

--- test
INSERT INTO unique_cats(cat_id, name, age) VALUES(1, 'Fred', 23);
INSERT INTO unique_cats(cat_id, name, age) VALUES(2, 'Louise', 3);
INSERT INTO unique_cats(cat_id, name, age) VALUES(1, 'James', 3);

DESC unique_cats; 
SELECT * FROM unique_cats; 

--- primary key + autoincrement
CREATE TABLE unique_cats2 (
    cat_id INT NOT NULL AUTO_INCREMENT,
    name VARCHAR(100),
    age INT,
    PRIMARY KEY (cat_id)
);

--- insert and test
INSERT INTO unique_cats2(name, age) VALUES('Skippy', 4);
INSERT INTO unique_cats2(name, age) VALUES('Jiff', 3);
INSERT INTO unique_cats2(name, age) VALUES('Jiff', 3);
INSERT INTO unique_cats2(name, age) VALUES('Jiff', 3);
INSERT INTO unique_cats2(name, age) VALUES('Skippy', 4);

SELECT * FROM unique_cats2; 

CREATE TABLE employees (
    id INT AUTO_INCREMENT NOT NULL,
    first_name VARCHAR(255) NOT NULL,
    last_name VARCHAR(255) NOT NULL,
    middle_name VARCHAR(255),
    age INT NOT NULL,
    current_status VARCHAR(255) NOT NULL DEFAULT 'employed',
    PRIMARY KEY(id)
);

--- other way 
CREATE TABLE employees (
    id INT AUTO_INCREMENT NOT NULL PRIMARY KEY,
    first_name VARCHAR(255) NOT NULL,
    last_name VARCHAR(255) NOT NULL,
    middle_name VARCHAR(255),
    age INT NOT NULL,
    current_status VARCHAR(255) NOT NULL DEFAULT 'employed'
);

INSERT INTO employees(first_name, last_name, age) VALUES
('Dora', 'Smith', 58);

SELECT * FROM cats; 
SELECT name FROM cats; 
SELECT age FROM cats; 
SELECT cat_id FROM cats; 
SELECT name, age FROM cats; 
SELECT cat_id, name, age FROM cats; 
SELECT age, breed, name, cat_id FROM cats; 
SELECT cat_id, name, age, breed FROM cats; 

--- where 
SELECT * FROM cats WHERE age=4; 
SELECT * FROM cats WHERE name='Egg'; 
SELECT * FROM cats WHERE name='egG'; 
SELECT cat_id FROM cats; 
SELECT name, breed FROM cats; 
SELECT name, age FROM cats WHERE breed='Tabby'; 
SELECT cat_id, age FROM cats WHERE cat_id=age; 
SELECT * FROM cats WHERE cat_id=age; 

--- alias
SELECT cat_id AS id, name FROM cats;
SELECT name AS 'cat name', breed AS 'kitty breed' FROM cats;
DESC cats;

--- update
UPDATE cats SET breed='Shorthair' WHERE breed='Tabby'; 
UPDATE cats SET age=14 WHERE name='Misty'; 

SELECT * FROM cats WHERE name='Jackson';
UPDATE cats SET name='Jack' WHERE name='Jackson';
SELECT * FROM cats WHERE name='Jackson';
SELECT * FROM cats WHERE name='Jack';
SELECT * FROM cats WHERE name='Ringo';
UPDATE cats SET breed='British Shorthair' WHERE name='Ringo';
SELECT * FROM cats WHERE name='Ringo';
SELECT * FROM cats;
SELECT * FROM cats WHERE breed='Maine Coon';
UPDATE cats SET age=12 WHERE breed='Maine Coon';
SELECT * FROM cats WHERE breed='Maine Coon';

DELETE FROM cats WHERE name='Egg';
SELECT * FROM cats;
SELECT * FROM cats WHERE name='egg';
DELETE FROM cats WHERE name='egg';
SELECT * FROM cats;
DELETE FROM cats;
SELECT * FROM cats WHERE age=4;
DELETE FROM cats WHERE age=4;
SELECT * FROM cats WHERE age=4;
SELECT * FROM cats;
SELECT *  FROM cats WHERE cat_id=age;
DELETE FROM cats WHERE cat_id=age;
DELETE FROM cats;
SELECT * FROM cats;

SELECT database();
 
CREATE DATABASE shirts_db;
 
use shirts_db;
 
SELECT database();
 
CREATE TABLE shirts
  (
    shirt_id INT NOT NULL AUTO_INCREMENT,
    article VARCHAR(100),
    color VARCHAR(100),
    shirt_size VARCHAR(100),
    last_worn INT,
    PRIMARY KEY(shirt_id)
  );
 
DESC shirts;
 
INSERT INTO shirts(article, color, shirt_size, last_worn) VALUES
('t-shirt', 'white', 'S', 10),
('t-shirt', 'green', 'S', 200),
('polo shirt', 'black', 'M', 10),
('tank top', 'blue', 'S', 50),
('t-shirt', 'pink', 'S', 0),
('polo shirt', 'red', 'M', 5),
('tank top', 'white', 'S', 200),
('tank top', 'blue', 'M', 15);
 
SELECT * FROM shirts;
 
INSERT INTO shirts(color, article, shirt_size, last_worn) 
VALUES('purple', 'polo shirt', 'medium', 50);
 
SELECT * FROM shirts;

SELECT article, color FROM shirts;
SELECT * FROM shirts WHERE shirt_size='M';
SELECT article, color, shirt_size, last_worn FROM shirts WHERE shirt_size='M';

SELECT * FROM shirts WHERE article='polo shirt';
UPDATE shirts SET shirt_size='L' WHERE article='polo shirt';
SELECT * FROM shirts WHERE article='polo shirt';
SELECT * FROM shirts;
SELECT * FROM shirts WHERE last_worn=15;
UPDATE shirts SET last_worn=0 WHERE last_worn=15;
SELECT * FROM shirts WHERE last_worn=15;
SELECT * FROM shirts WHERE last_worn=0;
SELECT * FROM shirts WHERE color='white';
UPDATE shirts SET color='off white', shirt_size='XS' WHERE color='white';
SELECT * FROM shirts WHERE color='white';
SELECT * FROM shirts WHERE color='off white';
SELECT * FROM shirts;

SELECT * FROM shirts;
SELECT * FROM shirts WHERE last_worn=200;
DELETE FROM shirts WHERE last_worn=200;
SELECT * FROM shirts WHERE article='tank top';
DELETE FROM shirts WHERE article='tank top';
SELECT * FROM shirts WHERE article='tank top';
SELECT * FROM shirts;
DELETE FROM shirts;
SELECT * FROM shirts;
DROP TABLE shirts;
show tables;
DESC shirts;

--- concat 
SELECT author_fname, author_lname FROM books;
 
CONCAT(x,y,z) // from slides
 
CONCAT(column, anotherColumn) // from slides
 
CONCAT(author_fname, author_lname)
 
CONCAT(column, 'text', anotherColumn, 'more text')
 
CONCAT(author_fname, ' ', author_lname)
 
CONCAT(author_fname, author_lname); // invalid syntax
 
SELECT CONCAT('Hello', 'World');
 
SELECT CONCAT('Hello', '...', 'World');
 
SELECT
  CONCAT(author_fname, ' ', author_lname)
FROM books;
 
SELECT
  CONCAT(author_fname, ' ', author_lname)
  AS 'full name'
FROM books;
 
SELECT author_fname AS first, author_lname AS last, 
  CONCAT(author_fname, ' ', author_lname) AS full
FROM books;
 
SELECT author_fname AS first, author_lname AS last, 
  CONCAT(author_fname, ', ', author_lname) AS full
FROM books;
 
SELECT CONCAT(title, '-', author_fname, '-', author_lname) FROM books;
 
SELECT 
    CONCAT_WS(' - ', title, author_fname, author_lname) 
FROM books;

--- substring

SELECT SUBSTRING('Hello World', 1, 4);
 
SELECT SUBSTRING('Hello World', 7);
 
SELECT SUBSTRING('Hello World', 3, 8);
 
SELECT SUBSTRING('Hello World', 3);
 
SELECT SUBSTRING('Hello World', -3);
 
SELECT SUBSTRING('Hello World', -7);
 
SELECT title FROM books;
 
SELECT SUBSTRING("Where I'm Calling From: Selected Stories", 1, 10);
 
SELECT SUBSTRING(title, 1, 10) FROM books;
 
SELECT SUBSTRING(title, 1, 10) AS 'short title' FROM books;
 
SELECT SUBSTR(title, 1, 10) AS 'short title' FROM books;
 
SELECT CONCAT
    (
        SUBSTRING(title, 1, 10),
        '...'
    )
FROM books;
 
source book_code.sql
 
SELECT CONCAT
    (
        SUBSTRING(title, 1, 10),
        '...'
    ) AS 'short title'
FROM books;
 
source book_code.sql

--- replace

SELECT REPLACE('Hello World', 'Hell', '%$#@');
SELECT REPLACE('Hello World', 'l', '7');
SELECT REPLACE('Hello World', 'o', '0');
SELECT REPLACE('HellO World', 'o', '*');
 
SELECT
  REPLACE('cheese bread coffee milk', ' ', ' and ');
 
SELECT REPLACE(title, 'e ', '3') FROM books;
 
-- SELECT
--    CONCAT
--    (
--        SUBSTRING(title, 1, 10),
--        '...'
--    ) AS 'short title'
-- FROM books;
 
SELECT
    SUBSTRING(REPLACE(title, 'e', '3'), 1, 10)
FROM books;
 
SELECT
    SUBSTRING(REPLACE(title, 'e', '3'), 1, 10) AS 'weird string'
FROM books;

--- reverse

SELECT REVERSE('Hello World');
SELECT REVERSE('meow meow');
SELECT REVERSE(author_fname) FROM books;
SELECT CONCAT('woof', REVERSE('woof'));
SELECT CONCAT(author_fname, REVERSE(author_fname)) FROM books;

--- char length

SELECT CHAR_LENGTH('Hello World');
SELECT author_lname, CHAR_LENGTH(author_lname) AS 'length' FROM books;
SELECT CONCAT(author_lname, ' is ', CHAR_LENGTH(author_lname), ' characters long') FROM books;

--- upper and lower

SELECT UPPER('Hello World');
SELECT LOWER('Hello World');
SELECT UPPER(title) FROM books;
SELECT CONCAT('MY FAVORITE BOOK IS ', UPPER(title)) FROM books;
SELECT CONCAT('MY FAVORITE BOOK IS ', LOWER(title)) FROM books;

--- string exercise

SELECT REVERSE(UPPER('Why does my cat look at me with such hatred?')); 
SELECT UPPER(REVERSE('Why does my cat look at me with such hatred?')); 
SELECT REPLACE(CONCAT('I', ' ', 'like', ' ', 'cats'), ' ', '-'); 
SELECT REPLACE(title, ' ', '->') AS title FROM books; 

SELECT 
   author_lname AS forwards,
   REVERSE(author_lname) AS backwards 
FROM books;

SELECT
   UPPER
   (
      CONCAT(author_fname, ' ', author_lname)
   ) AS 'full name in caps'
FROM books;

SELECT
   CONCAT(title, ' was released in ', released_year) AS blurb
FROM books;

SELECT
   title,
   CHAR_LENGTH(title) AS 'character count'
FROM books;

SELECT
   CONCAT(SUBSTRING(title, 1, 10), '...') AS 'short title',
   CONCAT(author_lname, ',', author_fname) AS author,
   CONCAT(stock_quantity, ' in stock') AS quantity
FROM books;

--- DISTINCT
SELECT author_lname FROM books;
SELECT DISTINCT author_lname FROM books;
SELECT author_fname, author_lname FROM books;
SELECT DISTINCT CONCAT(author_fname,' ', author_lname) FROM books;
SELECT DISTINCT author_fname, author_lname FROM books;

--- ORDER BY
SELECT author_lname FROM books;
 
SELECT author_lname FROM books ORDER BY author_lname;
 
SELECT title FROM books;
 
SELECT title FROM books ORDER BY title;
SELECT author_lname FROM books ORDER BY author_lname DESC;
 
SELECT released_year FROM books;
 
SELECT released_year FROM books ORDER BY released_year;
 
SELECT released_year FROM books ORDER BY released_year DESC;
 
SELECT released_year FROM books ORDER BY released_year ASC;
 
SELECT title, released_year, pages FROM books ORDER BY released_year;
 
SELECT title, pages FROM books ORDER BY released_year;
 
SELECT title, author_fname, author_lname 
FROM books ORDER BY 2;
 
SELECT title, author_fname, author_lname 
FROM books ORDER BY 3;
 
SELECT title, author_fname, author_lname 
FROM books ORDER BY 1;
 
SELECT title, author_fname, author_lname 
FROM books ORDER BY 1 DESC;
 
SELECT author_lname, title
FROM books ORDER BY 2;
 
SELECT author_fname, author_lname FROM books 
ORDER BY author_lname, author_fname;