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MySQL practical Tutorials part 2- inserting data into tables, CRUD, multiple inserts, warnings, primary key, not null, auto increment

 CODE: Inserting Data

Inserting Data


The "formula":


INSERT INTO table_name(column_name) VALUES (data);

For example:


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

SELECT * FROM cats; 


INSERT INTO table_name 

            (column_name, column_name) 

VALUES      (value, value), 

            (value, value), 

            (value, value);

INSERT Challenge Solution Code

CREATE TABLE people

  (

    first_name VARCHAR(20),

    last_name VARCHAR(20),

    age INT

  );

INSERT INTO people(first_name, last_name, age)

VALUES ('Tina', 'Belcher', 13);

INSERT INTO people(age, last_name, first_name)

VALUES (42, 'Belcher', 'Bob');

INSERT INTO people(first_name, last_name, age)

VALUES('Linda', 'Belcher', 45)

  ,('Phillip', 'Frond', 38)

  ,('Calvin', 'Fischoeder', 70);

DROP TABLE people; 


SELECT * FROM people; 


show tables; 


MySQL Warnings Code

DESC cats; 


Try Inserting a cat with a super long name:


INSERT INTO cats(name, age)

VALUES('This is some text blah blah blah blah blah text text text something about cats lalalalal meowwwwwwwwwww', 10);

Then view the warning:


SHOW WARNINGS; 


Try inserting a cat with incorrect data types:


INSERT INTO cats(name, age) VALUES('Lima', 'dsfasdfdas'); 


Then view the warning:


SHOW WARNINGS; 



NULL and NOT NULL Code

Try inserting a cat without an age:


INSERT INTO cats(name) VALUES('Alabama'); 


SELECT * FROM cats; 


Try inserting a nameless and ageless cat:


INSERT INTO cats() VALUES(); 



Define a new cats2 table with NOT NULL constraints:




CREATE TABLE cats2

  (

    name VARCHAR(100) NOT NULL,

    age INT NOT NULL

  );

DESC cats2; 


Now try inserting an ageless cat:


INSERT INTO cats2(name) VALUES('Texas'); 


View the new warnings:


SHOW WARNINGS; 


SELECT * FROM cats2; 


Do the same for a nameless cat:


INSERT INTO cats2(age) VALUES(7); 


SHOW WARNINGS; 


CODE: Setting Default Values 

Define a table with a DEFAULT name specified:


CREATE TABLE cats3

  (

    name VARCHAR(20) DEFAULT 'no name provided',

    age INT DEFAULT 99

  );

Notice the change when you describe the table:


DESC cats3; 


Insert a cat without a name:


INSERT INTO cats3(age) VALUES(13); 


Or a nameless, ageless cat:


INSERT INTO cats3() VALUES(); 


Combine NOT NULL and DEFAULT:


CREATE TABLE cats4

  (

    name VARCHAR(20) NOT NULL DEFAULT 'unnamed',

    age INT NOT NULL DEFAULT 99

  );

  

Notice The Difference:


INSERT INTO cats() VALUES();

 

SELECT * FROM cats;

 

INSERT INTO cats3() VALUES();

 

SELECT * FROM cats3;

 

INSERT INTO cats3(name, age) VALUES('Montana', NULL);

 

SELECT * FROM cats3;

 

INSERT INTO cats4(name, age) VALUES('Cali', NULL);



 CODE: Primary Keys

Define a table with a PRIMARY KEY constraint:


CREATE TABLE unique_cats

  (

    cat_id INT NOT NULL,

    name VARCHAR(100),

    age INT,

    PRIMARY KEY (cat_id)

  );

DESC unique_cats; 


Insert some new cats:


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);

Notice what happens:


SELECT * FROM unique_cats; 


Adding in AUTO_INCREMENT:


CREATE TABLE unique_cats2 (

    cat_id INT NOT NULL AUTO_INCREMENT,

    name VARCHAR(100),

    age INT,

    PRIMARY KEY (cat_id)

);

INSERT a couple new cats:


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);

Notice the difference:


SELECT * FROM unique_cats2; 


Table Constraints Exercise Solution

Defining The employees table:


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)

);

Another way of defining a primary key:




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'

);

A test INSERT:


INSERT INTO employees(first_name, last_name, age) VALUES

('Dora', 'Smith', 58);


INSERT INTO cats(name, age) VALUES(‘Taco’, 14); 


CODE: Preparing Our Data

Let's drop the existing cats table:


DROP TABLE cats; 


Recreate a new cats table:


CREATE TABLE cats 

  ( 

     cat_id INT NOT NULL AUTO_INCREMENT, 

     name   VARCHAR(100), 

     breed  VARCHAR(100), 

     age    INT, 

     PRIMARY KEY (cat_id) 

  ); 

DESC cats; 


And finally insert some new cats:


INSERT INTO cats(name, breed, age) 

VALUES ('Ringo', 'Tabby', 4),

       ('Cindy', 'Maine Coon', 10),

       ('Dumbledore', 'Maine Coon', 11),

       ('Egg', 'Persian', 4),

       ('Misty', 'Tabby', 13),

       ('George Michael', 'Ragdoll', 9),

       ('Jackson', 'Sphynx', 7);

Various Simple SELECT statements:

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; 


CODE: Introduction to WHERE

Select by age:


SELECT * FROM cats WHERE age=4; 


Select by name:


SELECT * FROM cats WHERE name='Egg'; 


Notice how it deals with case:


SELECT * FROM cats WHERE name='egG';


CODE: Select Challenges Solution

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; 


CODE: Introduction to Aliases


SELECT cat_id AS id, name FROM cats;

 

SELECT name AS 'cat name', breed AS 'kitty breed' FROM cats;

 

DESC cats;



CODE: Updating Data

Change tabby cats to shorthair:


UPDATE cats SET breed='Shorthair' WHERE breed='Tabby'; 


Another update:


UPDATE cats SET age=14 WHERE name='Misty'; 


CODE: Update Challenges Solution

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';



CODE: DELETING DATA

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;


CODE: CRUD Exercise Create Solution

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;



CODE: CRUD Exercise Read Solution

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';


CODE: CRUD Exercise Update Solution

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;


 CODE: CRUD Exercise Delete Solution

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;

CREATE TABLE cats

    (

        cat_id INT NOT NULL AUTO_INCREMENT,

        name VARCHAR(100),

        age INT,

        PRIMARY KEY(cat_id)

    );

DESC cats;

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