How can I extract a subset of an array starting from a specific index using Databricks SQL?
You can use the `slice` function in Databricks SQL to extract a subset of an array starting from a specific index. The syntax for the `slice` function is as follows:

`slice(expr, start, length)`

Here, `expr` is the array expression, `start` is the index from where you want to start the subset (array indices start at 1), and `length` is the number of elements you want in the subset. If `start` is negative, the function will start from the end of the array.

For example, if you have an array `array(1, 2, 3, 4)` and you want to extract a subset starting from index 2 with a length of 2, you would use the following query:

`SELECT slice(array(1, 2, 3, 4), 2, 2);`

This would return the array `[2,3]`. Similarly, if you want to start from the end of the array, you can use a negative index. For example, to extract a subset starting from the second last element with a length of 2, you would use:

`SELECT slice(array(1, 2, 3, 4), -2, 2);`

This would return the array `[3,4]`. If the requested array slice does not overlap with the actual length of the array, an empty array is returned.