Learn in the textbookData Analysis and Preprocessing
DefinitionCode design (コード設計) is the work of deciding the length, numbering scheme, and meaning of each digit of the codes (numbers or symbols) assigned to data items such as products and customers.
ExplanationA code exists to tell items apart uniquely, and if its digits or number ranges carry meaning, it can also be used for classification and aggregation. Leave room in the number of digits so that you do not run out of numbers as items are added later. To catch input errors, a check digit may also be added, a verification digit calculated from the other digits by a fixed rule.
AnalogyIt is like a postal code. The leading digits indicate a broad region and later digits narrow it down, so the number alone tells you roughly where a delivery is headed.
Memory hookRead the name literally: a digit whose only job is to check the others.