c# - ExecuteScalar调用引发异常 “Object reference not set to an instance of an object”

在单元测试中调试以下方法时，出现以下错误



当点击以下行时

result = (int)validateDatabase.ExecuteScalar();

方法是

    public static Boolean Validate(string argument1, string argument2)
    {
        int result = -1;

        using (var connection = new SqlConnection("connection string"))
        {
            SqlCommand validateDatabase = new SqlCommand("PROCEDURE NAME", connection);
            validateDatabase.CommandType = System.Data.CommandType.StoredProcedure;
            validateDatabase.Parameters.Add("@PARAMETER1", System.Data.SqlDbType.NVarChar).Value = argument1;
            validateDatabase.Parameters.Add("@PARAMETER2", System.Data.SqlDbType.NVarChar).Value = argument2;

            try
            {
                connection.Open();
                result = (int)validateDatabase.ExecuteScalar();
            }
            catch (SqlException exception) { Trace.WriteLine("exception.Message); }
            finally { connection.Close(); }
        }
        return (int)result == 0 ? true : false;
    }

最佳答案

根据MSDN，如果结果集为null，则ExecuteScalar返回null。这意味着您的演员表无效

请参阅此处以获得SqlCommand.ExecuteScalar文档

如果您要强制转换，请将其更改为可为空的int

result = (int?)validateDatabase.ExecuteScalar();

关于c# - ExecuteScalar调用引发异常 “Object reference not set to an instance of an object”，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/20117825/