Introduction

This is my first post. In his 20s, he is a fledgling engineer who has real estate, has no experience in his 30s, and has been offered a job hunting by the company he developed in-house. Today I will write about Mysql.

It is a program that extracts items that meet certain conditions from land data. We will pick up land with a unit price of 1 million yen or less.

From create TABLE.


--Create table(Column: id:m2 :price)
CREATE TABLE rands(
 id INT NOT NULL AUTO_INCREMENT,
 m2 INT,
 price INT,
 PRIMARY KEY (id)
);

--Then put the data in the table
INSERT INTO rands (m2, price) VALUES
 (200, 100000000),
 (300, 30000000),
 (500, 40000000),
 (100, 50000000);

--* SELECT (all data) and retrieve the data from the rands table in a form that meets the conditions with WHERE.
--Since it is a "unit price per tsubo", the constant 3.Insert 30578.

SELECT * FROM rands WHERE price / m2 * 3.30578 < 1000000 ;

This time I made a table and started by inserting data, If the data is accumulated,

SELECT *FROM table name WHERE condition;

You can get it at. that's all.

INT: It is a declaration that it is an integer.
NOT NULL: It is a description that NULL is not allowed. Even though it is a primary key, it will be filled with NULL.
AUTO_INCREMENT: A convenient method that automatically inserts ids in serial numbers.
PRIMARY KEY (id): It is a declaration that the data in the id column is the primary key. Without this, AUTO_INCREMENT cannot be used.
INSERT INTO: It is a description that the data to be declared earlier will be inserted.
VALUES: Values. In the above, it is (m2, price), so it means (m2 => 200, price => 1000000).

[RUBY] Use WHERE to retrieve the result calculated using the Mysql syntax

Introduction