I have this table seller whose columns are

```
id   mobile1
1    787811

```

I have another table with same columns ,I just want to update the mobile1 field from this table with the values from other table say "copy".
I have written this query

```
UPDATE seller
SET mobile1 = (
  SELECT SUBSTRING_INDEX(mobile1, '.', 1)
  FROM copy)
WHERE 1;

```

I am getting this obvious error when I run it.

> 
> Sub-query returns more than 1 row ,
>  Any way to do this??
> 
> 
>