SQL Server TVP Error

csharp
// Example in C# for SQL Server
var dataTable = new DataTable();
dataTable.Columns.Add("VariantColumn", typeof(int)); // Or typeof(decimal), typeof(string), etc.
// ... populate rows ...

sql
-- Original TVP (problematic)
CREATE TYPE MyVariantTVP AS TABLE (
    ID INT,
    Value sql_variant
);

-- Revised TVP (preferred)
CREATE TYPE MyTypedTVP AS TABLE (
    ID INT,
    IntValue INT NULL,
    DecimalValue DECIMAL(18, 2) NULL,
    StringValue VARCHAR(255) NULL
);

csharp
// Example in C# for calling the revised TVP
var dataTable = new DataTable();
dataTable.Columns.Add("ID", typeof(int));
dataTable.Columns.Add("IntValue", typeof(int));
dataTable.Columns.Add("DecimalValue", typeof(decimal));
dataTable.Columns.Add("StringValue", typeof(string));

dataTable.Rows.Add(1, 100, null, null);
dataTable.Rows.Add(2, null, 123.45m, null);
dataTable.Rows.Add(3, null, null, "Some Text");

sql
-- Example in stored procedure
CREATE PROCEDURE usp_ProcessMyData (@MyData MyTypedTVP READONLY)
AS
BEGIN
    SELECT
        ID,
        CASE
            WHEN IntValue IS NOT NULL THEN CAST(IntValue AS VARCHAR(50))
            WHEN DecimalValue IS NOT NULL THEN CAST(DecimalValue AS VARCHAR(50))
            WHEN StringValue IS NOT NULL THEN StringValue
            ELSE NULL
        END AS ProcessedValue
    FROM @MyData;
END;

csharp
// In your C# code, after populating DataTable
// Set a breakpoint here and inspect dataTable
SqlCommand cmd = new SqlCommand("YourStoredProcedure", connection);
cmd.CommandType = CommandType.StoredProcedure;

SqlParameter tvpParam = cmd.Parameters.AddWithValue("@YourTVP", dataTable);
tvpParam.SqlDbType = SqlDbType.Structured;
tvpParam.TypeName = "YourSchema.YourTVPName";

// Execute command...