We can use interval function to compute the days between two dates. In expressions in A3 and A4, @y and @m are interval function’s options. With these options, the function will use the year and the month as computational units in computing time interval. With function options, a function can meet multiple needs, extend its functions and avoid too many function names or function parameters.
2. Common function options
Some function options are common in esProc. They can be used by many functions.
@1 option and @a option are frequently used by functions to position, select and join, such as, A.pos(), A.select(), A.pmax(), A.pselect(), A.minp(), P.align(), etc.
Use of @a option can make functions that return the first query result by default return all eligible results. Contrary to @a, functions that return multiple members by default will return only the first query result by using @1 option.
We’ll look at the use of these two options through some examples: