小编Coo*_*ter的帖子

花费更多时间在PowerShell中提取SQL数据.遇到[System.DBNull] :: Value以及PowerShell在比较期间如何处理这些问题.

以下是我看到的行为示例以及变通方法

#DBNull values don't evaluate like Null...
    if([System.DBNull]::Value){"I would not expect this to display"}
    # The text displays.
    if([string][System.DBNull]::Value){"This won't display, but is not intuitive"}
    # The text does not display.

#DBNull does not let you use certain comparison operators
    10 -gt [System.DBNull]::Value 
    # Could not compare "10" to "". Error: "Cannot convert value "" to type "System.Int32". Error: "Object cannot be cast from DBNull to other types.""

    [System.DBNull]::Value -gt 10
    # Cannot compare "" because it …