如果在访问+ C＃的地方

Question

我怎么能在哪里做IF，在哪里我做过滤器，在我的情况下，我想要值为0的参数不会影响我的查询，只需忽略它们

string query = @"
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         
    IIF (@turno     == 0, AND P.codTurno = @turno       , )
    IIF (@grado     == 0, AND P.codGrado = @grado       , )
    IIF (@paralelo  == 0, AND P.codParalelo = @paralelo , )";


OleDbCommand command = new OleDbCommand(query, connection);

command.Parameters.AddWithValue("@fecha", dTPGrado.Value.Date);
command.Parameters.AddWithValue("@turno", codTurno);
command.Parameters.AddWithValue("@grado", codGrado);
command.Parameters.AddWithValue("@paralelo", codParalelo);

adapter.SelectCommand = command;
DataSet.Clear();

Answer 1

你可以在where语句中使用iif。但是语法起初并不直观。在哪里需要boolean子句，所以你要做的就是转换

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

至

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

请注意，每次参数@turno的值为0时，我们将其更改为-1（或者您确定不是的任何内容，并且不会在数据库的此列中。

所以最后你的SQL代码看起来应该是这样的

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