> For the complete documentation index, see [llms.txt](https://koonkim.gitbook.io/mongodb/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://koonkim.gitbook.io/mongodb/master/crud/read/exercises.md).

# Exercises

## Exercise 1

### Preliminary

* Import `people.json` into `lab4.people` (i.e. database name is `lab4` and collection name is `people`)

```bash
$ mongoimport -d lab4 -c people people.json
```

### Questions

* Find the documents whose age under 22.
* Find the documents whose age is between 22 and 26 (inclusive).
* Find the document whose name is “Lee” suppressing the profile.
* Find the documents whose name is not Lee.
* Find the documents whose name is “Lee” or “Park”.
* Find the documents whose name is not “Kim” or “Park” or “Lee”.

## Exercise 2

### Preliminary

* Import `inventory.json` into lab4.inventory

### Questions

* Find documents where the *tags* field contains below elements.
  * appliance, school, and book.
  * Hint: recall `$all` operator
* Find all documents but select at most three items in the *tags* field.
  * Hint: recall `$slice` operator
* Find all documents but select items from the second to the fourth in the *tags* field.
  * Hint: recall `$slice` operator with `[skip, limit]`
* Find documents that have brown color in the *qty* field.
  * Hint: recall `$elemMatch` operator

## Exercise 3

### Preliminary

* Import `store.json` to the store collection

### Questions

* Find documents where *buyer*'s *name* is "J.S. Lee"
  * Hint: Querying embedded document.
* Print purchased *items* where a *name* in a document is "iPhone Xs"
  * Hint: Querying embedded document, Projection
* Print the buyer’s purchase method where *items* contain the document that price is more than 2000$
  * Hint: < array.field >, Projection
* Find documents that don’t have carrier as key in attribute where the name is "Apple Watch Series 4"
  * Hint: `$elemMatch`, `$exists`

## **Exercise 4**

### **Preliminary**

* Import `store.json` to the store collection
  * Same with Exercise 3!

### Questions

* Find documents where buyer's name is "J.S. Lee"
  * Hint: Querying embedded document.&#x20;
* Print purchased items where a name in a document is "iPhone Xs".&#x20;
  * Hint: Querying embedded document, Projection&#x20;
* Print the buyer’s purchase method where items contain the document that price is more than 2000$.&#x20;
  * Hint: `<array.field>`, Projection&#x20;
* Find documents that don’t have carrier as key in attribute where the name is "Apple Watch Series 4"&#x20;
  * Hint: `$elemMatch`, `$exists`

## **Exercise 5**

### Preliminary

* Import `store.json` to the store collection
  * Same with Exercise 3!

### Questions

* Get the first three documents and print buyers field only.
* Skip a document and then print two documents
* Count documents in the store collection.

## **Exercise 6**

### Preliminary

* Using `grade.json` (import it using mongoimport)

### Questions

* The grade’s document can have among three types:
  * quiz, exam or homework
* Student id (sid) is from 0 to 99
* A document is lost, which contains a quiz score\
  1\. print lost document’s sid.\
  2\. Insert the quiz score (80) to the corresponding sid\
  3\. print the three students that have the highest quiz score.
* A simple example of the dataset looks like ...

```javascript
{"sid": 0, "type": "homework", "score": 69}
{"sid": 0, "type": "quiz" , "score": 29}
{"sid": 0, "type": "exam", "score": 86}
{"sid": 1, "type": "homework", "score": 2}
{"sid": 1, "type": "quiz" , "score": 6}
{"sid": 1, "type": "exam", "score": 67}
{"sid": 2, "type": "homework", "score": 13}
{"sid": 2, "type": "quiz" , "score": 91}
{"sid": 2, "type": "exam", "score": 76}
...
```

## **Exercise 7**

### Preliminary

* Using `grade.json` (import it using mongoimport)
  * Same with exercise 6

### Questions

* Write the score searching script
  * Search documents by filtering *type* and *score* fields

### Results

```
search > homework 13
sid homework
2 13
74 13
```

```
search > quiz 41-49
sid quiz
10 46
17 48
19 44
...
96 49
98 41
```

\
&#x20;
------