I need to concatenate text from various cells to a single cell in a row. This can go to an infinite number of rows.

How to use the CONCATENATE function in Google Sheets for doing this?

I also need to know how to use "if else if" in Google Sheets. For example: 

```
IF(A2="This")
JOIN(" ", A2,B2)
ELSE IF(A2="I")
JOIN(" ",A2,C2)
ELSE IF(A2="value")
JOIN(" ",A2,D2)

```

Is this possible in Google Sheets?

[![Concatenate Text From several cells into a single cell](https://i.stack.imgur.com/aNEDw.png)](https://i.stack.imgur.com/aNEDw.png)