将键映射到值的SQL函数

IF 用于流量控制。对于表达式,只需使用 CASE :

Insert Into IanaTable (IanaTimezone)
    Select 
        case
            when CONDITION1 then RESULT1
            when CONDITION2 then RESULT2
            ......
            when CONDITION100 the RESULT100
        end as IanaTimezone         
    From WindowsTzTable

编辑:由于OP表示他们更喜欢一个函数,因为相同的值将分配给多个列,所以我反对使用横向连接来别名表达式。这是更好的,因为即使是复制粘贴函数名也是湿的,而且容易出错。在这里:

Insert Into IanaTable (...)
    Select 
         q1.IanaTimezone as column1
        ,q1.IanaTimezone as column2
        ,q1.IanaTimezone as column3
        ,othervalue      as othercolumn
        ......
    From 
        WindowsTzTable
        cross apply
        (
            Select 
            case
                when CONDITION1 then RESULT1
                when CONDITION2 then RESULT2
                ......
                when CONDITION100 the RESULT100
            end as IanaTimezone 
        ) as q1