Problem description & analysis:

In the Excel table below, columns from the 2nd to the 6th have empty cells.

Task: From each column from the 2nd to the 6th, find the first and the last non-empty cells and concatenate the cell values they correspond in the 1st column using "to".

Solution:

Use SPL XLL to do this:

=spl("=d=E@2p(?),d.to(2,).(d(1)(~.pselect@z(~)) /""to""/ d(1)(~.pselect(~)))",A2:F15)

As shown in the picture below:

Explanation:

E@2p converts a two-layer sequence to a table sequence. pselect()function gets the position of the first member that meets the specified condition; u/z enables a search backward. to(2,) gets members from the 2nd to the last; (1) represent the 1stmember.