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Calling SQL Defined Functions in C# Using Inline SQL
In SQL Server, user-defined functions (UDFs) can enhance data manipulation and analysis capabilities. To invoke a scalar UDF from C# code, it's important to employ the correct approach.
Consider the following TSQL scalar UDF:
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
To call this function in C# code, one may attempt to use a stored procedure-like syntax:
public void TotalCupom(int cupom) { float SAIDA; SqlDataAdapter da2 = new SqlDataAdapter(); if (conex1.State == ConnectionState.Closed) { conex1.Open(); } SqlCommand Totalf = new SqlCommand("Tcupom", conex1); SqlParameter code1 = new SqlParameter("@code", SqlDbType.Int); code1.Value = cupom ; Totalf.CommandType = CommandType.StoredProcedure ; SAIDA = Totalf.ExecuteScalar(); return SAIDA; }
However, this approach is incorrect. To invoke a UDF, it's necessary to use inline SQL within a SqlCommand object:
SqlCommand Totalf = new SqlCommand("SELECT dbo.Tcupom(@code)", conex1);
It's crucial to remove the CommandType property, as UDFs are not stored procedures.
The modified code would appear as follows:
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; }
By employing inline SQL to call the UDF, developers can effectively harness the power of user-defined functions in their C# applications.
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