sqlDecimal to decimal clr stored procedure Unable to cast object of type 'System.Data.SqlTypes.SqlDecimal' to type 'System.IConvertible'

I'm new to this. I'm writing a clr stored procedure that calls another stored procedure to get a value that's used in a calculation.

A stored procedure returns int (I guess SqlInt32? the type of the value in the table is int) that is then needed to be converted to decimal.

Here's the code I have:

public static int CalculateMyValues(SqlDecimal aMyValue, SqlString aMyValueType, out SqlDecimal aResult)
{
    aResult = 0;
    try
    {
        SqlConnection conn = new SqlConnection("context connection=true");
        SqlCommand cmd = new SqlCommand("sp_GetType", conn);
        cmd.Parameters.AddWithValue("@myValueType", aMyValueType);
        cmd.CommandType = CommandType.StoredProcedure;
        conn.Open();

        object type = cmd.ExecuteScalar();

        conn.Close();

        decimal typeForCalculation = Convert.ToDecimal(type);
        decimal value = Convert.ToDecimal(aMyValue); // **

        Calculations calc = new Calculations(); 
        decimal result = calc.DoCalculation(typeForCalculation, value);

I get an exception (I think there see ******):

Unable to cast o开发者_StackOverflowbject of type 'System.Data.SqlTypes.SqlDecimal' to type 'System.IConvertible'.

Any ideas? Thanks.

The problem is that the Sql types don't implement the IConvertible interface, which is what Convert uses. You need to cast the type to a SqlDecimal, then use the Value property to obtain the decimal representation:

decimal typeForCalculation = ((SqlDecimal)type).Value;
decimal value = aMyValue.Value;

You need to be cautious here.

1) SqlDemical can contain Null value, so don't forget to check SqlDecimal.IsNull property.

2) Calling SqlDecimal.Value property may cause overflow exception, because not every SqlDecimal value can be converted to .NET's decimal without losing precision (SqlDecimal is 128 bits, .NET's decimal is 96 bits). One of the options to avoid overflow exception is to use SqlDecimal.Round() method.