Question

我的同事发现在以下上下文中使用IIF很难理解。

是否有更易读的替代方法？

DROP TABLE IF EXISTS #Cas;
CREATE TABLE #Cas( OP VARCHAR(10), BR  VARCHAR(10), SCORE INT)
INSERT INTO #Cas
    values
        ('A','X', 10),
        ('A','Y', 5),
        ('B','J', 6),
        ('C','Q', 50)

DROP TABLE IF EXISTS #Target;
CREATE TABLE #Target( OP VARCHAR(10), BR  VARCHAR(10) )
INSERT INTO #Target
    values
        ('A','ALL')

SELECT  C.OP,
        SUM(C.SCORE)
FROM    #Cas C
        INNER JOIN #Target T
            ON 
            C.OP = T.OP AND
            C.BR = IIF(T.BR = 'ALL', C.BR, T.BR)
GROUP BY C.OP

Answer 1

我通常使用NULL来识别特定情况（f.e。＆＃34; all＆＃34;）。因此，代码可能如下所示：

backgroundWorker1.DoWork += (senderWorker, e) =>
{
    try
    {
        // do something that might throw an exception
    }
    catch(Exception exception)
    {
        e.Result = exception; // this result is passed on to RunWorkerCompleted event
    }
}

替代在ON子句中使用IIF以提高可读性

1 个答案: