selecting a row from a table, using op...

 use case - you have a table in form of the FOLDER DAT, you want to pick from the rows of the table. Lets say they're a list of images. First, lets get rid of the first column, which just lists the filenames. We need the second column that displays a full path. Use a DAT Select node for this. Choose select Rows by Index, set appropriate last number & Columns also by Index (start and end will both be 1).

In the MOVIEFILEIN node, you could type -

op('NAME')[0,0]

to access the image in the first row. However if you want to do something a bit clever and use a CHOP named "INDEX", for example as the number to select the row, you can't just type -

op('NAME')[op('INDEX')[0],0]   <THIS WON'T WORK. And Touch Designer won't say why...

op('NAME')[int(op('INDEX')[0]),0]  <You have to change the data type to an int! 

so, by casting to an INT, the op('....') blabla works.