X++中SysComputedColumn::Sum用法求助，无相关文档参考

你用错方法了：SysComputedColumn::Sum()是聚合求和函数，用于GROUP BY场景下对单个字段做分组求和（比如统计某类物料的总净重），而非同一行内多个字段的加法运算。

要实现同一行内字段相加，直接用SysComputedColumn::returnField获取每个字段的SQL表达式，再用字符串拼接+运算符即可，以下是具体实现：

实现 grossWeight（TaraWeight + NetWeight） #

SysComputedColumn::returnStr(
    SysComputedColumn::returnField(tableStr(YourDataSourceTable), identifierStr(TaraWeight)) 
    + " + " 
    + SysComputedColumn::returnField(tableStr(YourDataSourceTable), identifierStr(NetWeight))
)

实现多字段求和（itemWeight + packingWeight + palletWeight） #

SysComputedColumn::returnStr(
    SysComputedColumn::returnField(tableStr(YourDataSourceTable), identifierStr(itemWeight)) 
    + " + " 
    + SysComputedColumn::returnField(tableStr(YourDataSourceTable), identifierStr(packingWeight)) 
    + " + " 
    + SysComputedColumn::returnField(tableStr(YourDataSourceTable), identifierStr(palletWeight))
)

注意事项 #

如果字段可能为NULL，直接相加会导致结果为NULL，需要用ISNULL处理空值：

SysComputedColumn::returnStr(
    "ISNULL(" + SysComputedColumn::returnField(tableStr(YourDataSourceTable), identifierStr(TaraWeight)) + ", 0)"
    + " + "
    + "ISNULL(" + SysComputedColumn::returnField(tableStr(YourDataSourceTable), identifierStr(NetWeight)) + ", 0)"
)

内容的提问来源于stack exchange，提问作者Šimon Šťastný