Finishes aggregate questions.

database/notes/06-sql-joins-aggregation-worksheet.md

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+# Queries
+
+## Joins
+
+1. Get all batch names along with their instructor names.
+
+```sql
+```
+
+2. Get all students along with their batch names if present else `NULL`.
+
+```sql
+```
+3. Get all students along with their batch names. Also, fetch all the batches which have no students.
+
+```sql
+```
+4. Get all the combinations of batches and instructors.
+
+```sql
+```
+5. Get all students with their instructors. If a student has no instructor, then show `NULL` for the instructor's name.
+
+```sql
+```
+
+## Aggregation
+1. Get the maximum IQ in all students (Try without aggregation first).
+
+```sql
+```
+
+2. Get the maximum IQ in all students (With aggregation).
+
+```sql
+```
+
+3. Get the oldest batch from the batches table.
+
+```sql
+```
+
+4. Fetch the number of batches that start with the word `Jedi`.
+
+```sql
+```
+
+5. Get the average IQ of all students (Without using `AVG`)
+
+```sql
+```
+
+6. Get the average IQ of students in all batches.
+
+```sql
+```
+7. Find the average IQ of students in each batch.
+
+```sql
+```
+
+8. Find the total number of students in each batch.
+
+```sql
+```
+
+9. Get the total number of batches taught by each instructor.
+
+```sql
+```
+
+10. Find the average IQ of students in batches with batch ID `1` and `2`.
+
+```sql
+```
+
+11. Find count of students that are part of batches that have average IQ greater than `120`.
+
+```sql
+```