Ruba week3 databases #26
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Week 2 LESSONPLAN
delete unnecessary info and typos in homework
…ce of timing between a column having an index and a column not having one
js file to fill up big db
week 3 typos and other minor changes
clarify homework question
…-assignment Homework -> Assignment update
Fixed assignment URL
…npm_and_yarn/Week2/QA-session-content/knex-2.4.0 Bump knex from 0.21.1 to 2.4.0 in /Week2/QA-session-content
fixed lucidchart link fixed drawio link
Corrected broken URL in databasew2 prepexw2
Improve SQL markup in READMEs
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Hi Ruba,
There are two points that you need to rework. I have made them explicit.
Please be aware of your git history. It contains a lot of irrelevant commits. Try to avoid dirty git history next time. git rebase is your good friend if you want a clean git history.
Feel free to ping me if you have questions!
Week3/Assignmen/transaction.js
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| const reduceBalanceQuery = ` | ||
| UPDATE account | ||
| SET balance = balance - 1000 | ||
| WHERE account_number = 1; | ||
| `; | ||
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| const addAmountQuery = ` | ||
| UPDATE account | ||
| SET balance = balance + 1000 | ||
| WHERE account_number = 2; | ||
| `; |
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In reality you cannot transfer money without enough balance. Hence it makes more sense if you add logic to check balances before transaction.
Week3/Assignmen/club.md
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| . Dinners => dinner_id, dinner_dat | ||
| . Venues => venue_code, venue_description | ||
| . Foods => food_code, food_descriptio | ||
| . Dinner_Venue => dinner_id, venue_cod |
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If it's one dinner to many venue code it's needed to use a separate relationship table. Otherwise having a column in dinner table for venue code is fine.
Week3/Assignmen/exercise4/CRUD.js
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| try { | ||
| await client.connect(); | ||
| const database = client.db("databaseWeek3"); | ||
| const collection = database.collection("bob_ross_episodes"); | ||
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| const newDocument = { | ||
| title: "Mountain View", | ||
| elements: ["mountains", "sky", "trees"] | ||
| }; | ||
| const createResult = await collection.insertOne(newDocument); | ||
| console.log(`New document created with the _id: ${createResult.insertedId}`); | ||
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| const cursor = collection.find(); | ||
| await cursor.forEach(doc => console.dir(doc)); | ||
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| const updateQuery = { title: "Mountain View" }; | ||
| const update = { $set: { title: "Beautiful Mountain View" } }; | ||
| const updateResult = await collection.updateOne(updateQuery, update); | ||
| console.log(`${updateResult.modifiedCount} document(s) updated`); | ||
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| const deleteQuery = { title: "Beautiful Mountain View" }; | ||
| const deleteResult = await collection.deleteOne(deleteQuery); | ||
| console.log(`${deleteResult.deletedCount} document(s) deleted`); |
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Needs rework: you need to write code for the questions in this file.
Week3/Assignmen/exercise3.js
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| function getPopulation(Country, name, code, cb) { | ||
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| const query = `SELECT Population FROM ?? WHERE Name = ? and code = ?`; | ||
| const values = [Country, name, code]; | ||
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| conn.query(query, values, (err, result) => { | ||
| if (err) return cb(err); | ||
| if (result.length === 0) return cb(new Error("Not found")); | ||
| cb(null, result[0].Population); | ||
| }); | ||
| } |
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Needs rework: I didn't see your answer for question 1 in exercise 3?
Week3/Assignmen/exercise3.js
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| function getPopulation(Country, name, code, cb) { | ||
| const query = `SELECT Population FROM ?? WHERE Name = ? AND code = ?`; | ||
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| const query = `SELECT Population FROM ?? WHERE Name = ? and code = ?`; | ||
| const values = [Country, name, code]; | ||
| conn.query(query, [Country, name, code], function (err, result) { | ||
| if (err) { | ||
| cb(err); | ||
| return; | ||
| } | ||
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| if (result.length == 0) { | ||
| cb(new Error("Not found")); | ||
| return; | ||
| } | ||
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| conn.query(query, values, (err, result) => { | ||
| if (err) return cb(err); | ||
| if (result.length === 0) return cb(new Error("Not found")); | ||
| cb(null, result[0].Population); | ||
| }); | ||
| } |
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Needs to work: maybe I missed something but I still didn't see your answer for the question 1 in exercise 3 about the example value that would take advantage of SQL-injection and ( fetch all the records in the database)?
Week3/Assignmen/exercise4/index.js
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| const updatedBushes = await collection.updateMany( | ||
| { elements: "BUSHES" }, | ||
| { $pull: { elements: "BUSHES" } } | ||
| ); | ||
| console.log(`Ran a command to remove all BUSHES and it updated ${updatedBushes.modifiedCount} episodes`); | ||
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| const addBushResult = await collection.updateMany( | ||
| { elements: { $in: ["BUSHES"] } }, | ||
| { $addToSet: { elements: "BUSH" } } | ||
| ); | ||
| console.log(`Ran a command to add 'BUSH' and it updated ${addBushResult.modifiedCount} episodes`); | ||
| } |
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Needs to work: From what I understand, you want to first remove all elements of BUSHES and then add BUSH. However, after you remove BUSHES, how can you find the correct documents in the second step? No elements contains BUSHES after deletion.
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