C# 如果在access+C中的何处

如何在where中执行IFF，在这里执行过滤器，在我的情况下，我希望到达值为0的参数不会影响我的查询，只需忽略它们即可

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可以在where语句中使用iif。但是语法一开始看起来并不直观。Where需要布尔子句，所以您应该做的是转换

IIF (@turno     == 0, AND P.codTurno = @turno       , )

到

请注意，每次参数@turno的值为0时，我们都会将其更改为-1或任何您确定不在且不会在数据库中此列中的值

因此，最终您的SQL代码应该如下所示

SELECT 
P.NombreCompleto
FROM (((((((Persona AS P 
LEFT JOIN MarcacionTemp AS MTemp ON P.codPersona = MTemp.codPersona) 
LEFT JOIN Horario AS Ho ON MTemp.codHorario = Ho.idHorario) 
LEFT JOIN TipoMarcacion AS TMar ON MTemp.codTipoMarcacion = TMar.idMarcacion) 
INNER JOIN Colegio AS C ON P.codColegio = C.codColegio) 
INNER JOIN Entidad AS E ON P.codEntidad = E.codEntidad) 
INNER JOIN Grado AS Gr ON P.codGrado = Gr.codGrado) 
INNER JOIN Paralelo AS Pa ON P.codParalelo = Pa.codParalelo) 
INNER JOIN Turno AS Tu ON P.codTurno = Tu.codTurno
WHERE P.codTipo = 4       
[and/or] IIF (@turno=0, -1, @turno) = P.codTurno
[and/or] IIF (@grado=0,-1, @grado) = P.codGrado 
[and/or] IIF (@paralelo=0, -1, @paralelo) = P.codParalelo

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如果没有，请使用内置的逻辑运算符，例如。。。和@turno=0或P.codTurno=@turno…请阅读。@AlexK。你是天才，但我只需要4个人请写下你的解决方案，非常简单good@AndrewMorton这不是问题，这些值工作得很好，请阅读说明，谢谢

IIF (@turno= 0, -1, @turno) = P.codTurno

SELECT 
P.NombreCompleto
FROM (((((((Persona AS P 
LEFT JOIN MarcacionTemp AS MTemp ON P.codPersona = MTemp.codPersona) 
LEFT JOIN Horario AS Ho ON MTemp.codHorario = Ho.idHorario) 
LEFT JOIN TipoMarcacion AS TMar ON MTemp.codTipoMarcacion = TMar.idMarcacion) 
INNER JOIN Colegio AS C ON P.codColegio = C.codColegio) 
INNER JOIN Entidad AS E ON P.codEntidad = E.codEntidad) 
INNER JOIN Grado AS Gr ON P.codGrado = Gr.codGrado) 
INNER JOIN Paralelo AS Pa ON P.codParalelo = Pa.codParalelo) 
INNER JOIN Turno AS Tu ON P.codTurno = Tu.codTurno
WHERE P.codTipo = 4       
[and/or] IIF (@turno=0, -1, @turno) = P.codTurno
[and/or] IIF (@grado=0,-1, @grado) = P.codGrado 
[and/or] IIF (@paralelo=0, -1, @paralelo) = P.codParalelo