DARYNA-TKACHENKO-WEEK3-DATABASE

Week3/homework/Exercise1/SQL-Normalization.md

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+### 3.1. Exercise 1 : SQL Normalization
+
+The manager of the dinner club would like to manage the information system that assists him to keep track of the dinners
+had by members.
+Because the manager is not an expert of Information Systems, (s)he uses the following table to store the information.
+Please help the manger by using the knowledge of database normal forms.
+Save all answers in a text file / MD file.
+
+1. What columns violate 1NF? 
+  -  1NF - need will be one value, same type, unique names, no dublicated. 1 Box - 1 thing
+   - dinner_date has many different date formats
+   - food_code has many values in one cell
+   - food_description has many values in one cell
+
+2. What entities do you recognize that could be extracted?
+   - entities - is things or objects. ERP diagram consist with : entities, atributes, relationships.
+   -  atributes is describe entities. relationships: one to many, many to many, many to one.
+  -  We can see these entities:
+   Member
+   Dinner
+   Venue
+   Food
+   Member–Dinner (members join dinners)
+   Dinner–Food (dinners have many foods)
+3. Name all the tables and columns that would make a 3NF compliant solution.
+- 3NF - Must be 2NF before.
+- No transitive dependency: column cannot depend on a non-key column.
+  -  1.Member
+   member_id
+   member_name
+   member_address
+   - 2.Dinner
+   dinner_id
+   dinner_date
+   venue_code
+   - 3.Venue
+   venue_code
+   venue_description
+   - 4.Food
+   food_code
+   food_description
+   - 5.Dinner_Food
+   dinner_id
+   food_code
+   - 6.Member_Dinner
+   member_id
+   dinner_id
+
+```
++-----------+---------------+----------------+-----------+-------------+------------+-------------------+-----------+------------------+
+| member_id | member_name   | member_address | dinner_id | dinner_date | venue_code | venue_description | food_code | food_description |
++-----------+---------------+----------------+-----------+-------------+------------+-------------------+-----------+------------------+
+|         1 | Amit          | 325 Max park   | D00001001 | 2020-03-15  | B01        | Grand Ball Room   | C1, C2    | Curry, Cake      |
+|         2 | Ben           | 24 Hudson lane | D00001002 | 2020/03/15  | B02        | Zoku Roof Top     | S1, C2    | Soup, Cake       |
+|         3 | Cristina      | 516 6th Ave    | D00001002 | 2020/03/15  | B02        | Zoku Roof Top     | S1, C2    | Soup, Cake       |
+|         4 | Dan           | 89 John St     | D00001003 | 20-03-2020  | B03        | Goat Farm         | P1, T1, M1| Pie, Tea, Mousse |
+|         1 | Amit          | 325 Max park   | D00001003 | 20-03-2020  | B03        | Goat Farm         | P1, T1, M1| Pie, Tea, Mousse |
+|         3 | Cristina      | 516 6th Ave    | D00001004 | Mar 25 '20  | B04        | Mama's Kitchen    | F1, M1    | Falafal, Mousse  |
+|         5 | Gabor         | 54 Vivaldi St  | D00001005 | Mar 26 '20  | B05        | Hungry Hungary    | G1, P2    | Goulash, Pasca   |
+|         6 | Hema          | 9 Peter St     | D00001003 | 01-04-2020  | B03        | Goat Farm         | P1, T1, M1| Pie, Tea, Mousse |
++-----------+---------------+----------------+-----------+-------------+------------+-------------------+-----------+------------------+
+```

Week3/homework/Exercise2/SQL-Transactions.md

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+### 3.2. Exercise 2 : SQL Transactions
+
+1. Create two tables `account` and `account_changes` (write transactions-create-tables.js file)
+2. `account` table should have following fields : `account_number, balance`.
+3. `account_changes` table should have the following
+   fields : `change_number, account_number, amount, changed_date, remark`.
+4. Choose the appropriate data types and keys for these tables.
+5. Insert some sample data in these tables. (write transactions-insert-values.js file)
+6. Transfer the amount of 1000 from account number 101 to account number 102 and log the changes in the
+   table `account_changes`.
+   Do this in a _single transaction_ (Write transaction.js file)
+
+Submit all three files (`transactions-create-tables.js`, `transactions-insert-values.js` and `transaction.js`).