ABAP數據結構激活時的錯誤，關於數據類型QUAN和其reference field

看看這種錯誤消息的一個例子：

combination reference table/field XXX does not exist

引發錯誤的字段類型爲LOSMENGE，字段名爲INSLO:

該字段的基本數據類型(Data Type)爲 QUAN，長度爲13.

根據ABAP幫助文檔, QUAN類型須要和某種單位字段結合在一塊兒，用於描述實際業務流程中的數量，好比 一本書，一件啤酒，一捆繩子等等。

A quantity field is a component of a structure, database table, or view of type QUAN defined in ABAP Dictionary, used to include a quantity in a specific unit. A quantity field must be associated with a unit key of a structure, database table, or view which determines the unit and the number of fractional digits. A unit key is a component of a structure, database table, or view of type UNIT defined in ABAP Dictionary and can contain a unit ID from the database table T006.

按照ABAP幫助文檔裏的規定，類型爲QUAN的字段，必須設置一個類型爲 UNIT 的字段做爲單位，兩者共同描述「數量」這個概念，缺乏單位，數量單位的語義就不完整。

A data element of data type QUAN is handled as a field of data type DEC and is stored in database tables in the BCD format. When creating a data element or a structure component of the data type QUAN in the ABAP Dictionary tool, any number of fractional digits can be defined. The default value is no fractional digits.

For every structure component of data type QUAN, a component of the same structure or of a different structure, database table, or view must be specified in the individual editing of the component as a reference field, which has the data type UNIT. This field is the unit key which determines the unit of the quantity. From a technical perspective, the data type UNIT is handled like a type CHAR with length 2.

更多Jerry的原創文章，盡在："汪子熙":