Question: Here are some sql tables:

**table USERS**

```
id
1

```

---

**table PROJECTS**

```
id
1

```

---

**table LOCATIONS**

```
id
1
2

```

---

**table USERS\_x\_PROJECTS**

```
id      id_USER      id_PROJECT
1       1            1

```

---

**table USERS\_x\_LOCATIONS**

```
id      id_USER      id_LOCATION
1       1            1

```

---

**table PROJECTS\_x\_LOCATIONS**

```
id      id_PROJECT      id_LOCATION
1       1               1
2       1               2

```

---

Users are linked to Projects. The links between Users and Projects are stored into USERS\_x\_PROJECTS.  
Users and Projects can be linked to Locations. The links are respectively stored into USERS\_x\_LOCATIONS and PROJECTS\_x\_LOCATIONS.

**Now lets say i'm user #1. What i want to do is fetch all projects with their locations where none of the projects's location is matching one of mine.**

**Expected result:**
With the example above, the expected result is to get an empty array because both the user and the only project in the database are linked to the location #1.

**Actual result:** 
I get the project #1

**What i tried:**

```
SELECT
    p.id id,
    GROUP_CONCAT(DISTINCT l.id SEPARATOR "#") l_ids
FROM
    PROJECTS p
LEFT JOIN
    PROJECTS_x_LOCATIONS pl ON pl.id_PROJECT = p.id
LEFT JOIN
    LOCATIONS l ON l.id = pl.id_LOCATION
WHERE
    l.id != 1
GROUP BY
    p.id 

```

Thanks for the help!

Answer: 
To check if a camera has a flash, use the `AVCaptureDevice.hasFlash` property on that camera.

It doesn't really make sense to use the back/front position to guess this, when there's already something that just tells you whether or not it has a flash.
@RazvanR solution works for that Apple AVCamera code, but just before it the code

```
// NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];

```

doesn't, and needs to use AVCapturePhotoOutput

The Swift version is

```
Swift: photoData = AVCapturePhotoOutput.jpegPhotoDataRepresentation(forJPEGSampleBuffer: photoSampleBuffer, previewPhotoSampleBuffer: previewPhotoSampleBuffer)

```

... but no idea what the Objective-C version is.