[kdbguru]

Hi,

As the question asks to extract “symbol list” of all the unique options, you should use “exec” rather than “select”. While “select” returns the result of a table type, “exec” for a single column would return a list of values.

uniqueOpts: exec distinct option_id from trade

[kdbguru]

What you are unintentionally doing is passing the list as a single argument. And so, it’s returning you back the projection of the aj function.

You should be able to differentiate between () & []. While () is used for a list, [] is used to pass the arguments to a function and “;” is used as a separator for the parameters.