diff --git a/database/code/create_database.sql b/database/code/create_database.sql
new file mode 100644
index 0000000..62700d4
--- /dev/null
+++ b/database/code/create_database.sql
@@ -0,0 +1,213 @@
+DROP DATABASE IF EXISTS `jedi_academy`;
+
+CREATE DATABASE `jedi_academy`;
+
+USE `jedi_academy`;
+
+SET
+    NAMES utf8;
+
+SET
+    character_set_client = utf8mb4;
+
+-- CREATE TABLES --
+CREATE TABLE `students` (
+    `id` int NOT NULL AUTO_INCREMENT,
+    `first_name` varchar(255) NOT NULL,
+    `last_name` varchar(255) NOT NULL,
+    `email` varchar(255) NOT NULL,
+    `phone` varchar(255),
+    `birth_date` date,
+    `address` varchar(255),
+    `iq` int,
+    `batch_id` int,
+    PRIMARY KEY (`id`)
+);
+
+CREATE TABLE `batches` (
+    `id` int NOT NULL AUTO_INCREMENT,
+    `name` varchar(255) NOT NULL,
+    `start_date` date NOT NULL,
+    `description` varchar(255),
+    `instructor_id` int,
+    PRIMARY KEY (`id`)
+);
+
+CREATE TABLE `instructors` (
+    `id` int NOT NULL AUTO_INCREMENT,
+    `first_name` varchar(255) NOT NULL,
+    `last_name` varchar(255) NOT NULL,
+    `email` varchar(255) NOT NULL,
+    `phone` varchar(255),
+    PRIMARY KEY (`id`)
+);
+
+-- ADD FOREIGN KEYS -- 
+ALTER TABLE
+    `students`
+ADD
+    FOREIGN KEY (`batch_id`) REFERENCES `batches`(`id`);
+
+ALTER TABLE
+    `batches`
+ADD
+    FOREIGN KEY (`instructor_id`) REFERENCES `instructors`(`id`);
+
+-- INSERT DATA --
+-- Instructors --
+INSERT INTO
+    `instructors` (`first_name`, `last_name`, `email`, `phone`)
+VALUES
+    ('Master', 'Yoda', 'y@jedi.com', '123-456-7890'),
+    (
+        'Obi-Wan',
+        'Kenobi',
+        'o@jedi.com',
+        '123-456-7890'
+    ),
+    (
+        'Sherlock',
+        'Holmes',
+        's@sherlock.ed',
+        '123-456-7890'
+    ),
+    (
+        'Rani',
+        'Laxmi Bai',
+        'r@rebelli.on',
+        '123-456-7890'
+    ),
+    (
+        'Thor',
+        'Odinson',
+        't@thunder.com',
+        '123-456-7890'
+    );
+
+-- Batches --
+INSERT INTO
+    `batches` (
+        `name`,
+        `start_date`,
+        `instructor_id`
+    )
+VALUES
+    (
+        'Jedi Academy 1',
+        '2012-01-01',
+        1
+    ),
+    (
+        'Jedi Academy 2',
+        '2014-01-01',
+        2
+    ),
+    (
+        'Sherlock Academy',
+        '2017-01-01',
+        3
+    ),
+    (
+        'Independence Academy',
+        '1857-01-01',
+        4
+    ),
+    (
+        'Love and Thunder Academy',
+        '2022-01-01',
+        5
+    );
+
+-- Students --
+INSERT INTO
+    `students` (
+        `first_name`,
+        `last_name`,
+        `email`,
+        `phone`,
+        `birth_date`,
+        `address`,
+        `iq`,
+        `batch_id`
+    )
+VALUES
+    (
+        'Anakin',
+        'Skywalker',
+        'darth@empire.blr',
+        '123-456-7890',
+        '1973-01-01',
+        'Tatooine',
+        130,
+        1
+    ),
+    (
+        'Luke',
+        'Skywalker',
+        'luke@resistance.com',
+        '123-456-7890',
+        '1994-01-01',
+        'Tatooine',
+        120,
+        2
+    ),
+    (
+        'Leia',
+        'Organa',
+        'leia@resistance.com',
+        '123-456-7890',
+        '1994-01-01',
+        'Alderaan',
+        130,
+        2
+    ),
+    (
+        'John',
+        'Watson',
+        'j@sherlock.ed',
+        '123-456-7890',
+        '1657-01-01',
+        'London',
+        130,
+        3
+    ),
+    (
+        'Mycroft',
+        'Holmes',
+        'm@sherlock.ed',
+        '123-456-7890',
+        '1657-01-01',
+        'London',
+        150,
+        3
+    ),
+    (
+        'Tantia',
+        'Tope',
+        't@rebelli.on',
+        '123-456-7890',
+        '1657-01-01',
+        'Jhansi',
+        130,
+        4
+    ),
+    (
+        'Jane',
+        'Foster',
+        'jane@th.or',
+        '123-456-7890',
+        '2022-01-01',
+        'New Asgard',
+        160,
+        5
+    ),
+    (
+        'Korg',
+        'Rock',
+        'korg@th.or',
+        '123-456-7890',
+        '2022-01-01',
+        'New Asgard',
+        80,
+        5
+    );
diff --git a/database/notes/04-sql-primer-worksheet-answers.md b/database/notes/04-sql-primer-worksheet-answers.md
new file mode 100644
index 0000000..e5e91dc
--- /dev/null
+++ b/database/notes/04-sql-primer-worksheet-answers.md
@@ -0,0 +1,210 @@
+
+# Queries
+
+## Insert queries
+1. Insert a row with all columns
+```sql
+    INSERT INTO students
+    VALUES (1, 'Tantia', 'Tope', 't@t.com', '1234567890', 1);
+```
+
+2. Insert a row with some columns
+```sql
+    INSERT INTO students (first_name, last_name)
+    VALUES ('Tantia', 'Tope');
+```
+
+---
+
+## Select Queries
+1. Get all students
+
+    ```sql
+    SELECT *
+    FROM students;
+    ```
+
+2. Get first and last name of all students
+
+    ```sql
+    SELECT first_name, last_name
+    FROM students;
+    ```
+
+3. Get first name of all students with output column name as `Student Name`
+    
+    ```sql
+    SELECT first_name AS "Student Name"
+    FROM students;
+    ```
+4. Get all unique addresses of all students
+        
+    ```sql
+    SELECT DISTINCT address FROM students;
+    ```
+5. Get all students with ID equal to 1
+    
+    ```sql
+    SELECT * FROM students WHERE id = 1;
+    ```
+6. Get all students with IQ greater than 150
+    
+    ```sql
+    SELECT * FROM students WHERE iq > 150;
+    ```
+7. Get all students with IQ less than 100
+    
+    ```sql
+    SELECT * FROM students WHERE iq < 100;
+    ```
+8. Get all students with IQ greater than 100 and less than150
+
+    ```sql
+    SELECT * FROM students
+    WHERE iq > 100 AND iq < 150;
+    ```
+9. Get all students with IQ greater than 100 or less than 150
+    
+    ```sql
+    SELECT * FROM students
+    WHERE iq BETWEEN 100 AND 150;
+    ```
+10. Get all students with first name `Tantia`
+    
+    ```sql
+    SELECT * FROM students WHERE first_name = 'Tantia';
+    ```
+11. Get all students with first name `Tantia` and last name `Tope`
+    
+    ```sql
+    SELECT * FROM students
+    WHERE first_name = 'Tantia' AND last_name = 'Tope';
+    ```
+12. Get all students with first name `John` or first name `Mycroft`
+    
+    ```sql
+    SELECT * FROM students
+    WHERE first_name = 'John' OR first_name = 'Mycroft';
+    ```
+13. Get all students with name `John Watson` or `Mycroft Holmes`
+    
+    ```sql
+    SELECT * FROM students
+    WHERE (first_name = 'John' AND last_name = 'Watson')
+    OR (first_name = 'Mycroft' AND last_name = 'Holmes');
+    ```
+14. Get all students without the first name `John`
+    
+    ```sql
+    SELECT * FROM students WHERE first_name <> 'John';
+    ```
+15. Get all students without the first name `John` or last name `Mycroft`
+    
+    ```sql
+    SELECT * FROM students
+    WHERE first_name <> 'John' AND last_name <> 'Mycroft';
+    ```
+16. Get all students with first name starting with `T`
+    
+    ```sql
+    SELECT * FROM students WHERE first_name LIKE 'T%';
+    ```
+17. Get all students with last name ending with `walker`
+    
+    ```sql
+    SELECT * FROM students WHERE last_name LIKE '%walker';
+    ```
+18. Get all students with first name containing `T`
+    
+    ```sql
+    SELECT * FROM students WHERE first_name LIKE '%T%';
+    ```
+19. Get all students with last name in the format `___walker`
+    ```sql
+    SELECT * FROM students WHERE last_name LIKE '___walker';
+    ```
+20. Get all students in Jhansi and London
+    
+    ```sql
+    SELECT * FROM students
+    WHERE address IN ('Jhansi', 'London');
+    ```
+21. Get all students which do not have a batch id
+    
+    ```sql
+    SELECT * FROM students WHERE batch_id IS NULL;
+    ```
+22. Get the first 5 students
+    
+    ```sql
+    SELECT * FROM students LIMIT 5;
+    ```
+23. Get the first 5 students sorted by IQ
+    
+    
+    ```sql
+    SELECT * FROM students ORDER BY iq LIMIT 5;
+    ```
+24. Get the first 5 students sorted by IQ in descending order
+    
+    ```sql
+    SELECT * FROM students ORDER BY iq DESC LIMIT 5;
+    ```
+25. Get the first 5 students sorted by IQ in descending order and then by first name
+    
+    ```sql
+    SELECT * FROM students 
+    ORDER BY iq DESC, first_name LIMIT 5;
+    ```
+
+---
+
+## Update Queries
+
+1. Update a row
+
+    ```sql
+    UPDATE students SET first_name = 'Tantia' WHERE id = 1;
+    ```
+2. Update a row with a condition
+
+    ```sql
+    UPDATE students SET first_name = 'Tantia' WHERE id = 1 AND first_name = 'John';
+    ```
+
+3. Update multiple columns
+
+    ```sql
+    UPDATE students SET first_name = 'Tantia', last_name = 'Tope' WHERE id = 1 AND first_name = 'John';
+    ```
+
+## Delete Queries
+
+1. Delete a row with a condition
+ 
+     ```sql
+     DELETE FROM students
+     WHERE id = 1 AND first_name = 'John';
+     ```
+ 
+2. Delete a multiple rows
+ 
+     ```sql
+     DELETE FROM students WHERE id IN (1, 2, 3);
+     ```
+
+## Joining Queries
+
+1. Get first name and last name of all students and their batch names
+    
+    ```sql
+    SELECT students.first_name, students.last_name, batches.name FROM students JOIN batches ON students.batch_id = batches.id;
+    ```
+2. Get first name and last name of all students and their instructor names
+    
+    ```sql
+    SELECT s.first_name, s.last_name, i.first_name, b.name, i.last_name 
+    FROM students s 
+        JOIN batches b ON s.batch_id = b.id
+        JOIN instructors i ON b.instructor_id = i.id;
+    ```
diff --git a/database/notes/04-sql-primer-worksheet.md b/database/notes/04-sql-primer-worksheet.md
new file mode 100644
index 0000000..267d00f
--- /dev/null
+++ b/database/notes/04-sql-primer-worksheet.md
@@ -0,0 +1,191 @@
+
+# Queries
+
+## Insert queries
+1. Insert a row with your name and all the other fields
+```sql
+    
+```
+
+1. Insert a row with just mandatory fields
+```sql
+    
+```
+
+---
+
+## Select Queries
+1. Get all students
+
+    ```sql
+    
+    ```
+
+2. Get first and last name of all students
+
+    ```sql
+    
+    ```
+
+3. Get first name of all students with output column name as `Student Name`
+    
+    ```sql
+    
+    ```
+4. Get all unique addresses of all students
+        
+    ```sql
+    
+    ```
+5. Get all students with ID equal to 1
+    
+    ```sql
+    
+    ```
+6. Get all students with IQ greater than 150
+    
+    ```sql
+    
+    ```
+7. Get all students with IQ less than 100
+    
+    ```sql
+    
+    ```
+8. Get all students with IQ greater than 100 and less than150
+
+    ```sql
+    
+    ```
+9. Get all students with IQ greater than 100 or less than 150
+    
+    ```sql
+     
+    ```
+10. Get all students with first name `Tantia`
+    
+    ```sql
+    
+    ```
+11. Get all students with first name `Tantia` and last name `Tope`
+    
+    ```sql
+    
+    ```
+12. Get all students with first name `John` or first name `Mycroft`
+    
+    ```sql
+    
+    ```
+13. Get all students with name `John Watson` or `Mycroft Holmes`
+    
+    ```sql
+    
+    ```
+14. Get all students without the first name `John`
+    
+    ```sql
+    
+    ```
+15. Get all students without the first name `John` or last name `Mycroft`
+    
+    ```sql
+    
+    ```
+16. Get all students with first name starting with `T`
+    
+    ```sql
+    
+    ```
+17. Get all students with last name ending with `walker`
+    
+    ```sql
+    
+    ```
+18. Get all students with first name containing `T`
+    
+    ```sql
+    
+    ```
+19. Get all students with last name in the format `___walker`
+    ```sql
+    
+    ```
+20. Get all students in Jhansi and London
+    
+    ```sql
+    
+    ```
+21. Get all students which do not have a batch id
+    
+    ```sql
+    
+    ```
+22. Get the first 5 students
+    
+    ```sql
+    
+    ```
+23. Get the first 5 students sorted by IQ
+    
+    
+    ```sql
+    
+    ```
+24. Get the first 5 students sorted by IQ in descending order
+    
+    ```sql
+    
+    ```
+25. Get the first 5 students sorted by IQ in descending order and then by first name
+    
+    ```sql
+    
+    ```
+
+---
+
+## Update Queries
+
+1. Update a row
+
+    ```sql
+    
+    ```
+2. Update a row with a condition
+
+    ```sql
+    
+    ```
+
+3. Update multiple columns
+
+    ```sql
+    
+    ```
+
+## Delete Queries
+
+1. Delete a row with a condition
+ 
+     ```sql
+     
+     ```
+ 
+2. Delete a multiple rows
+ 
+     ```sql
+     
+     ```
+
+## Joining Queries
+
+1. Get first name and last name of all students and their batch names
+    
+    ```sql
+    
+    ```
+2. Get first name and last name of all students and their instructor names
+    
+    ```sql
+    ```
\ No newline at end of file
diff --git a/database/notes/04-sql-primer.md b/database/notes/04-sql-primer.md
new file mode 100644
index 0000000..f07f4dd
--- /dev/null
+++ b/database/notes/04-sql-primer.md
@@ -0,0 +1,165 @@
+# SQL Primer
+
+## Agenda
+* CRUD with SQL
+* JOIN
+
+
+## CRUD with SQL
+
+### Create rows
+
+**Keyword**: `INSERT`
+**Syntax**: `INSERT INTO table_name (column1, column2, ...) VALUES (value1, value2, ...)`
+
+#### Examples
+
+1. Insert a row with all columns
+```sql
+    INSERT INTO students VALUES (1, 'Tantia', 'Tope', 't@t.com', '1234567890', 1);
+```
+
+2. Insert a row with some columns
+```sql
+    INSERT INTO students (first_name, last_name) VALUES ('Tantia', 'Tope');
+```
+### Read rows
+
+**Keyword**: `SELECT`
+**Syntax**: `SELECT column1, column2, ... FROM table_name WHERE condition ORDER BY column1, column2, ... ASC/DESC LIMIT #`
+
+#### Examples
+
+1. Get all rows
+
+    ```sql
+    SELECT * FROM students;
+    ```
+
+2. Get certain fields from all rows
+
+    ```sql
+    SELECT first_name, last_name FROM students;
+    ```
+3. Filter rows by condition
+    
+    ```sql
+    SELECT * FROM students WHERE first_name = 'Tantia';
+    ```
+4. Order rows by column
+    
+    ```sql
+    SELECT * FROM students ORDER BY first_name ASC;
+    ```
+5. Limit number of rows
+    
+    ```sql
+    SELECT * FROM students LIMIT 10;
+    ```
+
+#### Common operators for WHERE clause
+
+| Operator | Description           | Example                                                                     |
+| -------- | --------------------- | --------------------------------------------------------------------------- |
+| =        | Equal                 | `SELECT * FROM students WHERE first_name = 'Tantia'`                        |
+| != or <> | Not equal             | `SELECT * FROM students WHERE first_name != 'Tantia'`                       |
+| NOT      | NOT                   | `SELECT * FROM students WHERE NOT first_name = 'John'`                      |
+| >        | Greater than          | `SELECT * FROM students WHERE iq > 150`                                     |
+| <        | Less than             | `SELECT * FROM students WHERE age < 100`                                    |
+| >=       | Greater than or equal | `SELECT * FROM students WHERE age >= 18`                                    |
+| <=       | Less than or equal    | `SELECT * FROM students WHERE age <= 18`                                    |
+| AND      | AND                   | `SELECT * FROM students WHERE first_name = 'Tantia' AND last_name = 'Tope'` |
+| OR       | OR                    | `SELECT * FROM students WHERE first_name = 'John' OR last_name = 'Mycroft'` |
+| IN       | IN                    | `SELECT * FROM students WHERE first_name IN ('John', 'Mycroft')`            |
+| BETWEEN  | BETWEEN               | `SELECT * FROM students WHERE iq BETWEEN 100 AND 150`                       |
+| LIKE     | LIKE                  | `SELECT * FROM students WHERE first_name LIKE '%T%'`                        |
+| REGEXP   | REGEXP                | `SELECT * FROM students WHERE first_name REGEXP '^[A-Z]{1}'`                |
+| NULL     | NULL                  | `SELECT * FROM students WHERE first_name IS NULL`                           |
+| NOT NULL | NOT NULL              | `SELECT * FROM students WHERE first_name IS NOT NULL`                       |
+
+#### String matching wildcards
+
+With `LIKE` you can use the following two wildcard characters in the pattern:
+* `%` matches any number of characters, even zero characters.
+* `_` matches exactly one character.
+
+```sql
+SELECT * FROM students WHERE first_name LIKE 'T%';
+```
+
+```sql
+SELECT * FROM students WHERE first_name LIKE 'T_';
+```
+
+### Update rows
+
+**Keyword**: `UPDATE`
+**Syntax**: `UPDATE table_name SET column1 = value1, column2 = value2, ... WHERE condition`
+    
+##### Examples
+    
+  1. Update a row
+  
+      ```sql
+      UPDATE students SET first_name = 'Tantia' WHERE id = 1;
+      ```
+  2. Update a row with a condition
+  
+      ```sql
+      UPDATE students SET first_name = 'Tantia' WHERE id = 1 AND first_name = 'John';
+      ```
+  
+  3. Update multiple columns
+  
+      ```sql
+      UPDATE students SET first_name = 'Tantia', last_name = 'Tope' WHERE id = 1 AND first_name = 'John';
+      ```
+
+### Delete rows
+
+**Keyword**: `DELETE`
+**Syntax**: `DELETE FROM table_name WHERE condition`
+    
+##### Examples
+    
+
+1. Delete a row with a condition
+ 
+     ```sql
+     DELETE FROM students WHERE id = 1 AND first_name = 'John';
+     ```
+ 
+2. Delete a multiple rows
+ 
+     ```sql
+     DELETE FROM students WHERE id IN (1, 2, 3);
+     ```
+
+## Join
+
+Join is the widely-used clause in the SQL Server essentially to combine and retrieve data from two or more tables. In a real-world relational database, data is structured in many tables and which is why, there is a constant need to join these multiple tables based on logical relationships between them.
+
+### Inner join
+
+Inner Join clause in SQL Server creates a new table (not physical) by combining rows that have matching values in two or more tables. This join is based on a logical relationship (or a common field) between the tables and is used to retrieve data that appears in both tables.
+
+![Inner Join](https://i.stack.imgur.com/kZcvR.gif)
+
+Assume, we have two tables, Table A and Table B, that we would like to join using SQL Inner Join. The result of this join will be a new result set that returns matching rows in both these tables. The intersection part in black below shows the data retrieved using Inner Join.
+
+![Inner Join](https://www.sqlshack.com/wp-content/uploads/2019/06/venn-diagram-representation-of-sql-inner-join-.png)
+
+**Keyword**: `INNER JOIN` or simply `JOIN`
+**Syntax**: `SELECT column1, column2, ... FROM table_name1 JOIN table_name2 ON condition`
+
+For example, we want to get the batch names of all the students along with their names.
+| id  | first_name | last_name | batch_name |
+| --- | ---------- | --------- | ---------- |
+| 1   | John       | Watson    | Sherlock   |
+| 2   | Mycroft    | Holmes    | Sherlock   |
+
+This can be achieved by using the following SQL query:
+
+```sql
+SELECT s.first_name, s.last_name, b.batch_name FROM students s JOIN batches ON s.batch_id = b.id;
+```
\ No newline at end of file