Which Rate Applied on This Date?

Which Rate Applied on This Date?

Commission rates change over time: a salesperson earns 5% from January 1st, then 7% from March 1st, then 6% from June 1st. Nobody records an ending date — a rate simply stays in force until a newer one takes over. Business Central models currency exchange rates and price lists exactly this way: rows keyed by a code and a starting date, and the row that applies on any given date is the one with the latest starting date on or before that date. Your job is that lookup.

Requirements

The starter ships a table named "Commission Rate" — keep its name, field names and primary key exactly as they are, because the grading tests write rows into it directly:

Primary key: "Salesperson Code", "Starting Date".

Complete the codeunit named "Commission Rate Finder" with two public procedures:

procedure FindRateAt(SalespersonCode: Code[20]; AtDate: Date; var RatePct: Decimal): Boolean
procedure GetRateAt(SalespersonCode: Code[20]; AtDate: Date): Decimal

Rules:

1. A rate row applies at AtDate when its "Salesperson Code" equals SalespersonCode and its "Starting Date" is on or before AtDate. Among all applying rows, the one with the latest "Starting Date" wins.
2. FindRateAt returns true and sets RatePct to the winning row's "Rate %". On the very day a new rate starts, the new rate already applies — not the previous one.
3. When no row applies — the salesperson has no rows at all, or every row starts after AtDate — FindRateAt returns false and sets RatePct to 0, whatever value the caller passed in.
4. A rate of 0% is a real rate: when the winning row's "Rate %" is 0, FindRateAt returns true with RatePct = 0. "Found a 0% rate" and "found no rate" are different answers.
5. Rows belonging to other salespeople never influence the result — not even when the queried salesperson has no rows of their own.
6. GetRateAt returns the winning row's "Rate %", or 0 when no row applies.
7. Neither procedure may raise an error. The tests always seed real starting dates (never blank) and always pass a real AtDate.

What the tests check

The grading tests seed "Commission Rate" rows for freshly invented salesperson codes — several rates per salesperson, with the rate values generated at run time so constants can't pass — and probe FindRateAt and GetRateAt with dates on a starting date, between two starting dates, before the first starting date, and after the last one. One test seeds a 0% rate on top of an earlier non-zero rate and expects true with RatePct = 0. Another seeds a second salesperson whose rates would win if your code forgot to filter by salesperson, and expects the queried salesperson's own rate. The no-rate tests pass a deliberately dirty RatePct in and expect it back as 0.

Learn More

• Record.FindLast Method
• Record.SetRange Method
• Get, Find, and Next methods
• Table keys