How to Correctly Call SQL Defined Functions (UDFs) from C#?

Calling SQL Defined Functions in C#

Querying a database using SQL defined functions from C# code requires specific considerations when accessing user-defined functions (UDFs) within a SQL query. Here's how you can call a T-SQL scalar function named "Tcupom" from your C# code:

SQL Function:

create function TCupom (@cupom int)
returns float
as
begin
    declare @Tcu float;

    select @Tcu = sum (total) from alteraca2 where pedido = @cupom 

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

    return @tcu;
end

C# Code:

Error in Original Code:
The original C# code made two mistakes:

1. Calling the UDF's name directly as a command, which is not the correct syntax for accessing UDFs.
2. Setting the CommandType to StoredProcedure when it should be Text for UDFs.

Corrected Code:
The corrected code below demonstrates how to correctly call the "Tcupom" function from C#:

public void TotalCupom(int cupom)
{
    float SAIDA;
    SqlDataAdapter da2 = new SqlDataAdapter();

    if (conex1.State == ConnectionState.Closed)
    {
        conex1.Open();
    }

    SqlCommand Totalf = new SqlCommand("SELECT dbo.Tcupom(@code)", conex1);
    SqlParameter code1 = new SqlParameter("@code", SqlDbType.Int);
    code1.Value = cupom;

    SAIDA = Totalf.ExecuteScalar();

    return SAIDA;
}

Explanation:

• The SqlCommand object is constructed with an SQL query statement that includes the UDF's fully qualified name, dbo.Tcupom.
• The SqlParameter object is defined with the UDF's input parameter name, @code, and its value is set to the cupom parameter passed to the C# method.
• The ExecuteScalar() method is used to execute the UDF and retrieve its scalar result.

The above is the detailed content of How to Correctly Call SQL Defined Functions (UDFs) from C#?. For more information, please follow other related articles on the PHP Chinese website!