c# - C# 中具有 3 个参数的标量 sql 函数

Question

我用SQL写了这个函数

alter function TVprest (@emitente int, @mes int, @ano int)
returns float  
as
begin 
    declare @tcu float;

    select @tcu = sum(cast(vtprest as money)) 
    from ctrc 
    where emitente = @emitente  and MONTH (EMISSAODATA ) = @mes 
      and YEAR (EMISSAODATA)=@ano and status = 'A'

    if (@tcu is null)
        set @tcu = 0;

    return @tcu  
end

并尝试使用此代码在 C# 中调用相同的函数:

public double TVprest (int emitente, int mess, int anno)
{
        double saida;
        SqlConnection abre1 = Tconex.GetConnection();
        SqlDataAdapter da3 = new SqlDataAdapter();

        if (abre1.State == ConnectionState.Closed) { abre1.Open(); }

        SqlParameter emit = new SqlParameter("@emitente", SqlDbType.Int);
        emit.Value = emitente;

        SqlParameter mes = new SqlParameter("@mes", SqlDbType.Int);
        mes.Value = mess;

        SqlParameter ano = new SqlParameter("@ano", SqlDbType.Int);
        ano.Value = ano;

        SqlCommand TotalF = new SqlCommand("SELECT dbo.Tcupom(@emitente,@mes,@ano),", abre1);
        TotalF.CommandType = CommandType.Text;

        saida = Convert.ToDouble(TotalF.ExecuteScalar());
        return saida;
    }

运行时出现这个错误:

Failed to convert parameter value from SqlParameter to an Int32

怎么了？使用这些参数调用函数:

    double Tvprest = impx.TVprest(504, 5, 2013);
    lblVtprest.Text = Tvprest.ToString(); 

Answer 1

你还没有给你的命令添加参数

SqlCommand TotalF = new SqlCommand("SELECT dbo.Tcupom(@emitente,@mes,@ano),", abre1);
TotalF.Parameters.Add(emit);
TotalF.Parameters.Add(mes);
TotalF.Parameters.Add(ano);
saida = Convert.ToDouble(TotalF.ExecuteScalar());

但是，我认为您缺少解释问题中的内容。您有一个名为 TVprest 的函数，但您调用了一个 SELECT dbo.Tcupom。不清楚 Tcupom

是什么