Trying to update a new column with JSON,
i need to convert the selected data in to JSON first.

Here is my code (updated from comment):

```
SELECT a.col1 a.col2 b.col3 b.col4 
from table AS JSON 

```

and I want my output to look like:

`[{"col1": "value1", "col2": 2}, {"col3": "value3", "col4": "value4"}]`