I have the split shapefiles like same size tiles.
I want to show these merged on QGIS.

So, I tried to use Virtual Layer like following image.
[![enter image description here](https://i.stack.imgur.com/rhA4W.png)](https://i.stack.imgur.com/rhA4W.png)

And, I wrote following SQL:

```
select * from north
UNION
select * from central
UNION
select * from west

```

But, the boundary line of shapefile shown.
I want this,

[![enter image description here](https://i.stack.imgur.com/pgNqs.png)](https://i.stack.imgur.com/pgNqs.png)

In this case, how do I write SQL?