Ilias_Khugaev-w1-Databases #5
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yunchen4
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yunchen4
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Hi Ilias,
I am Chen and will review your assignments for the database module.
The assignment for week 1 has one point that needs rework. I have made it explicit. Otherwise it looks good. I also left some suggestions that can improve your query.
Please ping me on Slack when you finish the rework, or when you have any questions about database. 🙂
Week1/databases/assigment/meetup.js
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| try { | ||
| await connection.query('CREATE DATABASE IF NOT EXISTS meetup'); | ||
| await connection.query('USE meetup'); | ||
| await connection.query('CREATE TABLE Invitee (invitee_no INT NOT NULL PRIMARY KEY, invitee_name VARCHAR(25) NOT NULL, invited_by VARCHAR(25))'); |
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suggestion: when you define a column as PRIMARY KEY you don't need to add NOT NULL restriction, as the primary key needs to be not null.
And you can also add AUTO_INCREMENT for invitee_no, as it is a int. This way you won't need to specify invitee_no when you insert new rows into the table.
Week1/databases/assigment/meetup.js
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| await connection.query('CREATE DATABASE IF NOT EXISTS meetup'); | ||
| await connection.query('USE meetup'); | ||
| await connection.query('CREATE TABLE Invitee (invitee_no INT NOT NULL PRIMARY KEY, invitee_name VARCHAR(25) NOT NULL, invited_by VARCHAR(25))'); | ||
| await connection.query('CREATE TABLE Room (room_no INT NOT NULL PRIMARY KEY, room_name VARCHAR(25) NOT NULL, floor_number INT NOT NULL)'); |
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suggestion: Usually floor number is not a big number. If you want to decrease the size of your table, you can use tinyint for floor_number.
tinyint only takes 1 byte and int will take 4 bytes to store (doc).
| await connection.query('INSERT INTO Invitee VALUES (1, "Ilias Khugaev", "Ilia Bubnov")'); | ||
| await connection.query('INSERT INTO Invitee VALUES (2, "Anna Petrova", "Ilias Khugaev")'); | ||
| await connection.query('INSERT INTO Invitee VALUES (3, "Dmitry Sokolov", "Anna Petrova")'); | ||
| await connection.query('INSERT INTO Invitee VALUES (4, "Maria Ivanova", "Dmitry Sokolov")'); | ||
| await connection.query('INSERT INTO Invitee VALUES (5, "Oleg Smirnov", "Maria Ivanova")'); |
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If you add AUTO_INCREMENT for invitee_no then you don't need to specify 1,2,3,4,5 when inserting new invitees.
Week1/databases/assigment/world.js
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| // What's the top 10 countries by Surface Area? | ||
| await connection.query('SELECT name FROM country ORDER BY SurfaceArea LIMIT DESC 10'); |
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Need rework: This query (for top 10 countries by surface area) has syntax error. Please check it again.
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@yunchen4 Hi, thank you for your work. Here are my fixes! |
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